Signaling of sidelink beam training reference signal and sidelink discovery message before beam training response

ABSTRACT

Disclosed are techniques for wireless communication. In an aspect, an originator UE transmits a sidelink beam training (BT) reference signal (BTRS) a first number of times on each of a first set of beams, and a sidelink discovery message a second number of times on each of a second set of beams, wherein each beam from the second set of beams is associated with at least one beam from the first set of beams (e.g., 1:1 or N:1 mapping of first set of beams to second set of beams). At least one responder UE responds by transmitting, after the transmission of the sidelink BTRSs and the sidelink discovery messages, a BT response signal and a sidelink discovery response message on a beam corresponding to one of the first set of beams.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application for Patent is a Continuation of U.S.Non-Provisional application Ser. No. 17/332,604, entitled “SIGNALING OFSIDELINK BEAM TRAINING REFERENCE SIGNAL AND SIDELINK DISCOVERY MESSAGEBEFORE BEAM TRAINING RESPONSE,” filed May 27, 2021, assigned to theassignee hereof, and expressly incorporated herein by reference in itsentirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

Aspects of the disclosure relate generally to wireless communications.

2. Description of the Related Art

Wireless communication systems have developed through variousgenerations, including a first-generation analog wireless phone service(1G), a second-generation (2G) digital wireless phone service (includinginterim 2.5G and 2.75G networks), a third-generation (3G) high speeddata, Internet-capable wireless service and a fourth-generation (4G)service (e.g., Long Term Evolution (LTE) or WiMax). There are presentlymany different types of wireless communication systems in use, includingcellular and personal communications service (PCS) systems. Examples ofknown cellular systems include the cellular analog advanced mobile phonesystem (AMPS), and digital cellular systems based on code divisionmultiple access (CDMA), frequency division multiple access (FDMA), timedivision multiple access (TDMA), the Global System for Mobilecommunications (GSM), etc.

A fifth generation (5G) wireless standard, referred to as New Radio(NR), calls for higher data transfer speeds, greater numbers ofconnections, and better coverage, among other improvements. The 5Gstandard, according to the Next Generation Mobile Networks Alliance, isdesigned to provide data rates of several tens of megabits per second toeach of tens of thousands of users, with 1 gigabit per second to tens ofworkers on an office floor. Several hundreds of thousands ofsimultaneous connections should be supported in order to support largesensor deployments. Consequently, the spectral efficiency of 5G mobilecommunications should be significantly enhanced compared to the current4G standard. Furthermore, signaling efficiencies should be enhanced andlatency should be substantially reduced compared to current standards.

Leveraging the increased data rates and decreased latency of 5G, amongother things, vehicle-to-everything (V2X) communication technologies arebeing implemented to support autonomous driving applications, such aswireless communications between vehicles, between vehicles and theroadside infrastructure, between vehicles and pedestrians, etc.

SUMMARY

The following presents a simplified summary relating to one or moreaspects disclosed herein. Thus, the following summary should not beconsidered an extensive overview relating to all contemplated aspects,nor should the following summary be considered to identify key orcritical elements relating to all contemplated aspects or to delineatethe scope associated with any particular aspect. Accordingly, thefollowing summary has the sole purpose to present certain conceptsrelating to one or more aspects relating to the mechanisms disclosedherein in a simplified form to precede the detailed descriptionpresented below.

Sidelink communication may be implemented over higher bands (e.g., FR2,FR2x, FR4), which may complicate the discovery process (e.g., such thatbeam training is required). UEs on sidelink need to discovery each otherto setup a connection. In some designs, UEs need to perform beamtraining during the discovery procedure, particularly for discovery overhigher bands as noted above. In some designs, without beam training, itis difficult for UEs to communicate the sidelink discovery messages andsidelink discovery response messages. In some legacy designs, beamtraining is performed before the sidelink discovery message iscommunicated. Hence, all candidate responder UEs that detect a beamtraining (BT) reference signal (BTRS) may transmit the BT response(e.g., because the candidate responder UEs do not yet know if they areinterested in connecting to the initiator UE). This creates high systemoverhead in scenarios where candidate responder UEs perform beamtraining and transmit BT responses, but ultimately receive the sidelinkdiscovery message and decide not to connect (e.g., no sidelink discoveryresponse message is sent).

Aspects of the disclosure are directed to a discovery procedure wherebyan initiator UE transmits sidelink discovery message(s) and BTRS(s)before a BT response is received from candidate responder UEs. In thiscase, the candidate responder UEs have an opportunity to review thesidelink discovery message(s) before transmission of a BT response. Suchaspects may provide various technical advantages, such as reducingdiscovery overhead, reducing spectral interference, and so on.

In an aspect, a method of operating an initiator user equipment (UE)includes transmitting a sidelink beam training (BT) reference signal(BTRS) a first number of times on each of a first set of beams;transmitting a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and receiving, from at least one responder UE after the transmission ofthe sidelink BTRSs and the sidelink discovery messages, a BT responsesignal and a sidelink discovery response message on a beam correspondingto one of the first set of beams.

In some aspects, the transmission of the sidelink discovery messagesfollows the transmission of the sidelink BTRSs.

In some aspects, the transmission of the sidelink BTRSs follows thetransmission of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are transmitted in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are transmitted in order betweensuccessively adjacent beams among the second set of beams, or acombination thereof.

In some aspects, the sidelink BTRSs are transmitted via interleaving ofthe first set of beams, or the sidelink discovery messages aretransmitted via interleaving of the second set of beams, or acombination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, a method of operating responder user equipment (UE)includes receiving, from an initiator UE, a sidelink beam training (BT)reference signal (BTRS) a first number of times on each of a first setof beams; receiving, from the initiator UE, a sidelink discovery messagea second number of times on each of a second set of beams, wherein eachbeam from the second set of beams is associated with at least one beamfrom the first set of beams; and transmitting, to the initiator UE, a BTresponse signal and a sidelink discovery response message on a beam thatcorresponds to one of the first set of beams.

In some aspects, the reception of the sidelink discovery messagesfollows the reception of the sidelink BTRSs.

In some aspects, the reception of the sidelink BTRSs follows thereception of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are received in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are received in order between successivelyadjacent beams among the second set of beams, or a combination thereof.

In some aspects, the sidelink BTRSs are received via interleaving of thefirst set of beams, or the sidelink discovery messages are received viainterleaving of the second set of beams, or a combination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, an initiator user equipment (UE) includes a memory; atleast one transceiver; and at least one processor communicativelycoupled to the memory and the at least one transceiver, the at least oneprocessor configured to: transmit, via the at least one transceiver, asidelink beam training (BT) reference signal (BTRS) a first number oftimes on each of a first set of beams; transmit, via the at least onetransceiver, a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and receive, via the at least one transceiver, from at least oneresponder UE after the transmission of the sidelink BTRSs and thesidelink discovery messages, a BT response signal and a sidelinkdiscovery response message on a beam corresponding to one of the firstset of beams.

In some aspects, the transmission of the sidelink discovery messagesfollows the transmission of the sidelink BTRSs.

In some aspects, the transmission of the sidelink BTRSs follows thetransmission of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are transmitted in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are transmitted in order betweensuccessively adjacent beams among the second set of beams, or acombination thereof.

In some aspects, the sidelink BTRSs are transmitted via interleaving ofthe first set of beams, or the sidelink discovery messages aretransmitted via interleaving of the second set of beams, or acombination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, a responder user equipment (UE) includes a memory; atleast one transceiver; and at least one processor communicativelycoupled to the memory and the at least one transceiver, the at least oneprocessor configured to: receive, via the at least one transceiver, froman initiator UE, a sidelink beam training (BT) reference signal (BTRS) afirst number of times on each of a first set of beams; receive, via theat least one transceiver, from the initiator UE, a sidelink discoverymessage a second number of times on each of a second set of beams,wherein each beam from the second set of beams is associated with atleast one beam from the first set of beams; and transmit, via the atleast one transceiver, to the initiator UE, a BT response signal and asidelink discovery response message on a beam that corresponds to one ofthe first set of beams.

In some aspects, the reception of the sidelink discovery messagesfollows the reception of the sidelink BTRSs.

In some aspects, the reception of the sidelink BTRSs follows thereception of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are received in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are received in order between successivelyadjacent beams among the second set of beams, or a combination thereof.

In some aspects, the sidelink BTRSs are received via interleaving of thefirst set of beams, or the sidelink discovery messages are received viainterleaving of the second set of beams, or a combination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, an initiator user equipment (UE) includes means fortransmitting a sidelink beam training (BT) reference signal (BTRS) afirst number of times on each of a first set of beams; means fortransmitting a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and means for receiving, from at least one responder UE after thetransmission of the sidelink BTRSs and the sidelink discovery messages,a BT response signal and a sidelink discovery response message on a beamcorresponding to one of the first set of beams.

In some aspects, the transmission of the sidelink discovery messagesfollows the transmission of the sidelink BTRSs.

In some aspects, the transmission of the sidelink BTRSs follows thetransmission of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are transmitted in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are transmitted in order betweensuccessively adjacent beams among the second set of beams, or acombination thereof.

In some aspects, the sidelink BTRSs are transmitted via interleaving ofthe first set of beams, or the sidelink discovery messages aretransmitted via interleaving of the second set of beams, or acombination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, a responder user equipment (UE) includes means forreceiving, from an initiator UE, a sidelink beam training (BT) referencesignal (BTRS) a first number of times on each of a first set of beams;means for receiving, from the initiator UE, a sidelink discovery messagea second number of times on each of a second set of beams, wherein eachbeam from the second set of beams is associated with at least one beamfrom the first set of beams; and means for transmitting, to theinitiator UE, a BT response signal and a sidelink discovery responsemessage on a beam that corresponds to one of the first set of beams.

In some aspects, the reception of the sidelink discovery messagesfollows the reception of the sidelink BTRSs.

In some aspects, the reception of the sidelink BTRSs follows thereception of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are received in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are received in order between successivelyadjacent beams among the second set of beams, or a combination thereof.

In some aspects, the sidelink BTRSs are received via interleaving of thefirst set of beams, or the sidelink discovery messages are received viainterleaving of the second set of beams, or a combination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, a non-transitory computer-readable medium storingcomputer-executable instructions that, when executed by an initiatoruser equipment (UE), cause the UE to: transmit a sidelink beam training(BT) reference signal (BTRS) a first number of times on each of a firstset of beams; transmit a sidelink discovery message a second number oftimes on each of a second set of beams, wherein each beam from thesecond set of beams is associated with at least one beam from the firstset of beams; and receive, from at least one responder UE after thetransmission of the sidelink BTRSs and the sidelink discovery messages,a BT response signal and a sidelink discovery response message on a beamcorresponding to one of the first set of beams.

In some aspects, the transmission of the sidelink discovery messagesfollows the transmission of the sidelink BTRSs.

In some aspects, the transmission of the sidelink BTRSs follows thetransmission of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are transmitted in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are transmitted in order betweensuccessively adjacent beams among the second set of beams, or acombination thereof.

In some aspects, the sidelink BTRSs are transmitted via interleaving ofthe first set of beams, or the sidelink discovery messages aretransmitted via interleaving of the second set of beams, or acombination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

In an aspect, a non-transitory computer-readable medium storingcomputer-executable instructions that, when executed by a responder userequipment (UE), cause the UE to: receive, from an initiator UE, asidelink beam training (BT) reference signal (BTRS) a first number oftimes on each of a first set of beams; receive, from the initiator UE, asidelink discovery message a second number of times on each of a secondset of beams, wherein each beam from the second set of beams isassociated with at least one beam from the first set of beams; andtransmit, to the initiator UE, a BT response signal and a sidelinkdiscovery response message on a beam that corresponds to one of thefirst set of beams.

In some aspects, the reception of the sidelink discovery messagesfollows the reception of the sidelink BTRSs.

In some aspects, the reception of the sidelink BTRSs follows thereception of the sidelink discovery messages.

In some aspects, the first number of times is the same as the secondnumber of times.

In some aspects, the first number of times is greater than the secondnumber of times.

In some aspects, each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

In some aspects, there is a 1:1 mapping between the first set of beamsand the second set of beams.

In some aspects, each beam among the first set of beams is associatedwith a first width, and each beam among the second set of beams isassociated with a second width that is wider than the first width.

In some aspects, there is a N:1 mapping between the first set of beamsand the second set of beams, with N being greater than 1.

In some aspects, two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

In some aspects, the sidelink BTRSs are received in order betweensuccessively adjacent beams among the first set of beams, or thesidelink discovery messages are received in order between successivelyadjacent beams among the second set of beams, or a combination thereof.

In some aspects, the sidelink BTRSs are received via interleaving of thefirst set of beams, or the sidelink discovery messages are received viainterleaving of the second set of beams, or a combination thereof.

In some aspects, the BT response signal comprises a preamble or amessage.

Other objects and advantages associated with the aspects disclosedherein will be apparent to those skilled in the art based on theaccompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofvarious aspects of the disclosure and are provided solely forillustration of the aspects and not limitation thereof.

FIG. 1 illustrates an example wireless communications system, accordingto aspects of the disclosure.

FIGS. 2A and 2B illustrate example wireless network structures,according to aspects of the disclosure.

FIGS. 3A, 3B, and 3C are simplified block diagrams of several sampleaspects of components that may be employed in a user equipment (UE), abase station, and a network entity, respectively, and configured tosupport communications as taught herein.

FIG. 4 is a block diagram illustrating various components of an exampleuser equipment (UE), according to aspects of the disclosure.

FIG. 5 illustrates an example of a wireless communications system thatsupports unicast sidelink establishment, according to aspects of thedisclosure.

FIG. 6 is a diagram illustrating an example wireless node incommunication with an example UE, according to aspects of thedisclosure.

FIG. 7 illustrates a discovery procedure in accordance with aspects ofthe disclosure.

FIG. 8A illustrates a comparative illustration depicting the relativewidths of beams in accordance with aspects of the disclosure.

FIG. 8B illustrates frequency utilizations of BTRS and DMRS inaccordance with aspects of the disclosure.

FIG. 9 illustrates an exemplary process of communications according toan aspect of the disclosure.

FIG. 10 illustrates an exemplary process of communications according toan aspect of the disclosure.

FIG. 11 illustrates a discovery procedure based on an exampleimplementation of the processes of FIGS. 9-10 in accordance with aspectsof the disclosure.

FIG. 12 illustrates a signaling sequence associated with the discoveryprocedure of FIG. 11 .

FIG. 13 illustrates a discovery procedure based on an exampleimplementation of the processes of FIGS. 9-10 in accordance with aspectsof the disclosure.

FIG. 14 illustrates a discovery procedure based on an exampleimplementation of the processes of FIGS. 9-10 in accordance with aspectsof the disclosure.

FIG. 15 illustrates a discovery procedure based on an exampleimplementation of the processes of FIGS. 9-10 in accordance with aspectsof the disclosure.

FIG. 16 illustrates a signaling sequence associated with the discoveryprocedure of FIG. 15 .

FIG. 17 illustrates a discovery procedure based on an exampleimplementation of the processes of FIGS. 9-10 in accordance with aspectsof the disclosure.

FIG. 18 illustrates a discovery procedure based on an exampleimplementation of the processes of FIGS. 9-10 in accordance with aspectsof the disclosure.

FIG. 19 is a conceptual data flow diagram illustrating the data flowbetween different means/components in exemplary apparatuses inaccordance with an aspect of the disclosure.

FIGS. 20-21 are diagrams illustrating examples of hardwareimplementations for apparatuses employing processing systems inaccordance with aspects of the disclosure.

DETAILED DESCRIPTION

Aspects of the disclosure are provided in the following description andrelated drawings directed to various examples provided for illustrationpurposes. Alternate aspects may be devised without departing from thescope of the disclosure. Additionally, well-known elements of thedisclosure will not be described in detail or will be omitted so as notto obscure the relevant details of the disclosure.

The words “exemplary” and/or “example” are used herein to mean “servingas an example, instance, or illustration.” Any aspect described hereinas “exemplary” and/or “example” is not necessarily to be construed aspreferred or advantageous over other aspects. Likewise, the term“aspects of the disclosure” does not require that all aspects of thedisclosure include the discussed feature, advantage or mode ofoperation.

Those of skill in the art will appreciate that the information andsignals described below may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the description below may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof, depending inpart on the particular application, in part on the desired design, inpart on the corresponding technology, etc.

Further, many aspects are described in terms of sequences of actions tobe performed by, for example, elements of a computing device. It will berecognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. Additionally, the sequence(s)of actions described herein can be considered to be embodied entirelywithin any form of non-transitory computer-readable storage mediumhaving stored therein a corresponding set of computer instructions that,upon execution, would cause or instruct an associated processor of adevice to perform the functionality described herein. Thus, the variousaspects of the disclosure may be embodied in a number of differentforms, all of which have been contemplated to be within the scope of theclaimed subject matter. In addition, for each of the aspects describedherein, the corresponding form of any such aspects may be describedherein as, for example, “logic configured to” perform the describedaction.

As used herein, the terms “user equipment” (UE), “vehicle UE” (V-UE),“pedestrian UE” (P-UE), and “base station” are not intended to bespecific or otherwise limited to any particular radio access technology(RAT), unless otherwise noted. In general, a UE may be any wirelesscommunication device (e.g., vehicle on-board computer, vehiclenavigation device, mobile phone, router, tablet computer, laptopcomputer, asset locating device, wearable (e.g., smartwatch, glasses,augmented reality (AR)/virtual reality (VR) headset, etc.), vehicle(e.g., automobile, motorcycle, bicycle, etc.), Internet of Things (IoT)device, etc.) used by a user to communicate over a wirelesscommunications network. A UE may be mobile or may (e.g., at certaintimes) be stationary, and may communicate with a radio access network(RAN). As used herein, the term “UE” may be referred to interchangeablyas a “mobile device,” an “access terminal” or “AT,” a “client device,” a“wireless device,” a “subscriber device,” a “subscriber terminal,” a“subscriber station,” a “user terminal” or UT, a “mobile terminal,” a“mobile station,” or variations thereof.

A V-UE is a type of UE and may be any in-vehicle wireless communicationdevice, such as a navigation system, a warning system, a heads-updisplay (HUD), an on-board computer, an in-vehicle infotainment system,an automated driving system (ADS), an advanced driver assistance system(ADAS), etc. Alternatively, a V-UE may be a portable wirelesscommunication device (e.g., a cell phone, tablet computer, etc.) that iscarried by the driver of the vehicle or a passenger in the vehicle. Theterm “V-UE” may refer to the in-vehicle wireless communication device orthe vehicle itself, depending on the context. A P-UE is a type of UE andmay be a portable wireless communication device that is carried by apedestrian (i.e., a user that is not driving or riding in a vehicle).Generally, UEs can communicate with a core network via a RAN, andthrough the core network the UEs can be connected with external networkssuch as the Internet and with other UEs. Of course, other mechanisms ofconnecting to the core network and/or the Internet are also possible forthe UEs, such as over wired access networks, wireless local area network(WLAN) networks (e.g., based on Institute of Electrical and ElectronicsEngineers (IEEE) 802.11, etc.) and so on.

A base station may operate according to one of several RATs incommunication with UEs depending on the network in which it is deployed,and may be alternatively referred to as an access point (AP), a networknode, a NodeB, an evolved NodeB (eNB), a next generation eNB (ng-eNB), aNew Radio (NR) Node B (also referred to as a gNB or gNodeB), etc. A basestation may be used primarily to support wireless access by UEsincluding supporting data, voice and/or signaling connections for thesupported UEs. In some systems a base station may provide purely edgenode signaling functions while in other systems it may provideadditional control and/or network management functions. A communicationlink through which UEs can send signals to a base station is called anuplink (UL) channel (e.g., a reverse traffic channel, a reverse controlchannel, an access channel, etc.). A communication link through whichthe base station can send signals to UEs is called a downlink (DL) orforward link channel (e.g., a paging channel, a control channel, abroadcast channel, a forward traffic channel, etc.). As used herein theterm traffic channel (TCH) can refer to either an UL/reverse orDL/forward traffic channel.

The term “base station” may refer to a single physicaltransmission-reception point (TRP) or to multiple physical TRPs that mayor may not be co-located. For example, where the term “base station”refers to a single physical TRP, the physical TRP may be an antenna ofthe base station corresponding to a cell (or several cell sectors) ofthe base station. Where the term “base station” refers to multipleco-located physical TRPs, the physical TRPs may be an array of antennas(e.g., as in a multiple-input multiple-output (MIMO) system or where thebase station employs beamforming) of the base station. Where the term“base station” refers to multiple non-co-located physical TRPs, thephysical TRPs may be a distributed antenna system (DAS) (a network ofspatially separated antennas connected to a common source via atransport medium) or a remote radio head (RRH) (a remote base stationconnected to a serving base station). Alternatively, the non-co-locatedphysical TRPs may be the serving base station receiving the measurementreport from the UE and a neighbor base station whose reference radiofrequency (RF) signals the UE is measuring. Because a TRP is the pointfrom which a base station transmits and receives wireless signals, asused herein, references to transmission from or reception at a basestation are to be understood as referring to a particular TRP of thebase station.

In some implementations that support positioning of UEs, a base stationmay not support wireless access by UEs (e.g., may not support data,voice, and/or signaling connections for UEs), but may instead transmitreference RF signals to UEs to be measured by the UEs and/or may receiveand measure signals transmitted by the UEs. Such base stations may bereferred to as positioning beacons (e.g., when transmitting RF signalsto UEs) and/or as location measurement units (e.g., when receiving andmeasuring RF signals from UEs).

An “RF signal” comprises an electromagnetic wave of a given frequencythat transports information through the space between a transmitter anda receiver. As used herein, a transmitter may transmit a single “RFsignal” or multiple “RF signals” to a receiver. However, the receivermay receive multiple “RF signals” corresponding to each transmitted RFsignal due to the propagation characteristics of RF signals throughmultipath channels. The same transmitted RF signal on different pathsbetween the transmitter and receiver may be referred to as a “multipath”RF signal. As used herein, an RF signal may also be referred to as a“wireless signal” or simply a “signal” where it is clear from thecontext that the term “signal” refers to a wireless signal or an RFsignal.

FIG. 1 illustrates an example wireless communications system 100,according to aspects of the disclosure. The wireless communicationssystem 100 (which may also be referred to as a wireless wide areanetwork (WWAN)) may include various base stations 102 (labelled “BS”)and various UEs 104. The base stations 102 may include macro cell basestations (high power cellular base stations) and/or small cell basestations (low power cellular base stations). In an aspect, the macrocell base stations 102 may include eNBs and/or ng-eNBs where thewireless communications system 100 corresponds to an LTE network, orgNBs where the wireless communications system 100 corresponds to a NRnetwork, or a combination of both, and the small cell base stations mayinclude femtocells, picocells, microcells, etc.

The base stations 102 may collectively form a RAN and interface with acore network 174 (e.g., an evolved packet core (EPC) or 5G core (5GC))through backhaul links 122, and through the core network 174 to one ormore location servers 172 (e.g., a location management function (LMF) ora secure user plane location (SUPL) location platform (SLP)). Thelocation server(s) 172 may be part of core network 174 or may beexternal to core network 174. In addition to other functions, the basestations 102 may perform functions that relate to one or more oftransferring user data, radio channel ciphering and deciphering,integrity protection, header compression, mobility control functions(e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, RAN sharing, multimedia broadcast multicast service(MBMS), subscriber and equipment trace, RAN information management(RIM), paging, positioning, and delivery of warning messages. The basestations 102 may communicate with each other directly or indirectly(e.g., through the EPC/5GC) over backhaul links 134, which may be wiredor wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. In an aspect, one or more cellsmay be supported by a base station 102 in each geographic coverage area110. A “cell” is a logical communication entity used for communicationwith a base station (e.g., over some frequency resource, referred to asa carrier frequency, component carrier, carrier, band, or the like), andmay be associated with an identifier (e.g., a physical cell identifier(PCI), an enhanced cell identifier (ECI), a virtual cell identifier(VCI), a cell global identifier (CGI), etc.) for distinguishing cellsoperating via the same or a different carrier frequency. In some cases,different cells may be configured according to different protocol types(e.g., machine-type communication (MTC), narrowband IoT (NB-IoT),enhanced mobile broadband (eMBB), or others) that may provide access fordifferent types of UEs. Because a cell is supported by a specific basestation, the term “cell” may refer to either or both the logicalcommunication entity and the base station that supports it, depending onthe context. In some cases, the term “cell” may also refer to ageographic coverage area of a base station (e.g., a sector), insofar asa carrier frequency can be detected and used for communication withinsome portion of geographic coverage areas 110.

While neighboring macro cell base station 102 geographic coverage areas110 may partially overlap (e.g., in a handover region), some of thegeographic coverage areas 110 may be substantially overlapped by alarger geographic coverage area 110. For example, a small cell basestation 102′ (labelled “SC” for “small cell”) may have a geographiccoverage area 110′ that substantially overlaps with the geographiccoverage area 110 of one or more macro cell base stations 102. A networkthat includes both small cell and macro cell base stations may be knownas a heterogeneous network. A heterogeneous network may also includehome eNBs (HeNBs), which may provide service to a restricted group knownas a closed subscriber group (CSG).

The communication links 120 between the base stations 102 and the UEs104 may include uplink (also referred to as reverse link) transmissionsfrom a UE 104 to a base station 102 and/or downlink (DL) (also referredto as forward link) transmissions from a base station 102 to a UE 104.The communication links 120 may use MIMO antenna technology, includingspatial multiplexing, beamforming, and/or transmit diversity. Thecommunication links 120 may be through one or more carrier frequencies.Allocation of carriers may be asymmetric with respect to downlink anduplink (e.g., more or less carriers may be allocated for downlink thanfor uplink).

The wireless communications system 100 may further include a wirelesslocal area network (WLAN) access point (AP) 150 in communication withWLAN stations (STAs) 152 via communication links 154 in an unlicensedfrequency spectrum (e.g., 5 GHz). When communicating in an unlicensedfrequency spectrum, the WLAN STAs 152 and/or the WLAN AP 150 may performa clear channel assessment (CCA) or listen before talk (LBT) procedureprior to communicating in order to determine whether the channel isavailable.

The small cell base station 102′ may operate in a licensed and/or anunlicensed frequency spectrum. When operating in an unlicensed frequencyspectrum, the small cell base station 102′ may employ LTE or NRtechnology and use the same 5 GHz unlicensed frequency spectrum as usedby the WLAN AP 150. The small cell base station 102′, employing LTE/5Gin an unlicensed frequency spectrum, may boost coverage to and/orincrease capacity of the access network. NR in unlicensed spectrum maybe referred to as NR-U. LTE in an unlicensed spectrum may be referred toas LTE-U, licensed assisted access (LAA), or MulteFire.

The wireless communications system 100 may further include a mmW basestation 180 that may operate in millimeter wave (mmW) frequencies and/ornear mmW frequencies in communication with a UE 182. Extremely highfrequency (EHF) is part of the RF in the electromagnetic spectrum. EHFhas a range of 30 GHz to 300 GHz and a wavelength between 1 millimeterand 10 millimeters. Radio waves in this band may be referred to as amillimeter wave. Near mmW may extend down to a frequency of 3 GHz with awavelength of 100 millimeters. The super high frequency (SHF) bandextends between 3 GHz and 30 GHz, also referred to as centimeter wave.Communications using the mmW/near mmW radio frequency band have highpath loss and a relatively short range. The mmW base station 180 and theUE 182 may utilize beamforming (transmit and/or receive) over a mmWcommunication link 184 to compensate for the extremely high path lossand short range. Further, it will be appreciated that in alternativeconfigurations, one or more base stations 102 may also transmit usingmmW or near mmW and beamforming. Accordingly, it will be appreciatedthat the foregoing illustrations are merely examples and should not beconstrued to limit the various aspects disclosed herein.

Transmit beamforming is a technique for focusing an RF signal in aspecific direction. Traditionally, when a network node (e.g., a basestation) broadcasts an RF signal, it broadcasts the signal in alldirections (omni-directionally). With transmit beamforming, the networknode determines where a given target device (e.g., a UE) is located(relative to the transmitting network node) and projects a strongerdownlink RF signal in that specific direction, thereby providing afaster (in terms of data rate) and stronger RF signal for the receivingdevice(s). To change the directionality of the RF signal whentransmitting, a network node can control the phase and relativeamplitude of the RF signal at each of the one or more transmitters thatare broadcasting the RF signal. For example, a network node may use anarray of antennas (referred to as a “phased array” or an “antennaarray”) that creates a beam of RF waves that can be “steered” to pointin different directions, without actually moving the antennas.Specifically, the RF current from the transmitter is fed to theindividual antennas with the correct phase relationship so that theradio waves from the separate antennas add together to increase theradiation in a desired direction, while cancelling to suppress radiationin undesired directions.

Transmit beams may be quasi-co-located, meaning that they appear to thereceiver (e.g., a UE) as having the same parameters, regardless ofwhether or not the transmitting antennas of the network node themselvesare physically co-located. In NR, there are four types ofquasi-co-location (QCL) relations. Specifically, a QCL relation of agiven type means that certain parameters about a second reference RFsignal on a second beam can be derived from information about a sourcereference RF signal on a source beam. Thus, if the source reference RFsignal is QCL Type A, the receiver can use the source reference RFsignal to estimate the Doppler shift, Doppler spread, average delay, anddelay spread of a second reference RF signal transmitted on the samechannel. If the source reference RF signal is QCL Type B, the receivercan use the source reference RF signal to estimate the Doppler shift andDoppler spread of a second reference RF signal transmitted on the samechannel. If the source reference RF signal is QCL Type C, the receivercan use the source reference RF signal to estimate the Doppler shift andaverage delay of a second reference RF signal transmitted on the samechannel. If the source reference RF signal is QCL Type D, the receivercan use the source reference RF signal to estimate the spatial receiveparameter of a second reference RF signal transmitted on the samechannel. In receive beamforming, the receiver uses a receive beam toamplify RF signals detected on a given channel. For example, thereceiver can increase the gain setting and/or adjust the phase settingof an array of antennas in a particular direction to amplify (e.g., toincrease the gain level of) the RF signals received from that direction.Thus, when a receiver is said to beamform in a certain direction, itmeans the beam gain in that direction is high relative to the beam gainalong other directions, or the beam gain in that direction is thehighest compared to the beam gain in that direction of all other receivebeams available to the receiver. This results in a stronger receivedsignal strength (e.g., reference signal received power (RSRP), referencesignal received quality (RSRQ), signal-to-interference-plus-noise ratio(SINR), etc.) of the RF signals received from that direction.

Transmit and receive beams may be spatially related. A spatial relationmeans that parameters for a second beam (e.g., a transmit or receivebeam) for a second reference signal can be derived from informationabout a first beam (e.g., a receive beam or a transmit beam) for a firstreference signal. For example, a UE may use a particular receive beam toreceive a reference downlink reference signal (e.g., synchronizationsignal block (SSB)) from a base station. The UE can then form a transmitbeam for sending an uplink reference signal (e.g., sounding referencesignal (SRS)) to that base station based on the parameters of thereceive beam.

Note that a “downlink” beam may be either a transmit beam or a receivebeam, depending on the entity forming it. For example, if a base stationis forming the downlink beam to transmit a reference signal to a UE, thedownlink beam is a transmit beam. If the UE is forming the downlinkbeam, however, it is a receive beam to receive the downlink referencesignal. Similarly, an “uplink” beam may be either a transmit beam or areceive beam, depending on the entity forming it. For example, if a basestation is forming the uplink beam, it is an uplink receive beam, and ifa UE is forming the uplink beam, it is an uplink transmit beam.

In 5G, the frequency spectrum in which wireless nodes (e.g., basestations 102/180, UEs 104/182) operate is divided into multiplefrequency ranges, FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). mmWfrequency bands generally include the FR2, FR3, and FR4 frequencyranges. As such, the terms “mmW” and “FR2” or “FR3” or “FR4” maygenerally be used interchangeably.

In a multi-carrier system, such as 5G, one of the carrier frequencies isreferred to as the “primary carrier” or “anchor carrier” or “primaryserving cell” or “PCell,” and the remaining carrier frequencies arereferred to as “secondary carriers” or “secondary serving cells” or“SCells.” In carrier aggregation, the anchor carrier is the carrieroperating on the primary frequency (e.g., FR1) utilized by a UE 104/182and the cell in which the UE 104/182 either performs the initial radioresource control (RRC) connection establishment procedure or initiatesthe RRC connection re-establishment procedure. The primary carriercarries all common and UE-specific control channels, and may be acarrier in a licensed frequency (however, this is not always the case).A secondary carrier is a carrier operating on a second frequency (e.g.,FR2) that may be configured once the RRC connection is establishedbetween the UE 104 and the anchor carrier and that may be used toprovide additional radio resources. In some cases, the secondary carriermay be a carrier in an unlicensed frequency. The secondary carrier maycontain only necessary signaling information and signals, for example,those that are UE-specific may not be present in the secondary carrier,since both primary uplink and downlink carriers are typicallyUE-specific. This means that different UEs 104/182 in a cell may havedifferent downlink primary carriers. The same is true for the uplinkprimary carriers. The network is able to change the primary carrier ofany UE 104/182 at any time. This is done, for example, to balance theload on different carriers. Because a “serving cell” (whether a PCell oran SCell) corresponds to a carrier frequency/component carrier overwhich some base station is communicating, the term “cell,” “servingcell,” “component carrier,” “carrier frequency,” and the like can beused interchangeably.

For example, still referring to FIG. 1 , one of the frequencies utilizedby the macro cell base stations 102 may be an anchor carrier (or“PCell”) and other frequencies utilized by the macro cell base stations102 and/or the mmW base station 180 may be secondary carriers(“SCells”). The simultaneous transmission and/or reception of multiplecarriers enables the UE 104/182 to significantly increase its datatransmission and/or reception rates. For example, two 20 MHz aggregatedcarriers in a multi-carrier system would theoretically lead to atwo-fold increase in data rate (i.e., 40 MHz), compared to that attainedby a single 20 MHz carrier.

In the example of FIG. 1 , any of the illustrated UEs (shown in FIG. 1as a single UE 104 for simplicity) may receive signals 124 from one ormore Earth orbiting space vehicles (SVs) 112 (e.g., satellites). In anaspect, the SVs 112 may be part of a satellite positioning system that aUE 104 can use as an independent source of location information. Asatellite positioning system typically includes a system of transmitters(e.g., SVs 112) positioned to enable receivers (e.g., UEs 104) todetermine their location on or above the Earth based, at least in part,on positioning signals (e.g., signals 124) received from thetransmitters. Such a transmitter typically transmits a signal markedwith a repeating pseudo-random noise (PN) code of a set number of chips.While typically located in SVs 112, transmitters may sometimes belocated on ground-based control stations, base stations 102, and/orother UEs 104. A UE 104 may include one or more dedicated receiversspecifically designed to receive signals 124 for deriving geo locationinformation from the SVs 112. In a satellite positioning system, the useof signals 124 can be augmented by various satellite-based augmentationsystems (SBAS) that may be associated with or otherwise enabled for usewith one or more global and/or regional navigation satellite systems.For example an SBAS may include an augmentation system(s) that providesintegrity information, differential corrections, etc., such as the WideArea Augmentation System (WAAS), the European Geostationary NavigationOverlay Service (EGNOS), the Multi-functional Satellite AugmentationSystem (MSAS), the Global Positioning System (GPS) Aided Geo AugmentedNavigation or GPS and Geo Augmented Navigation system (GAGAN), and/orthe like. Thus, as used herein, a satellite positioning system mayinclude any combination of one or more global and/or regional navigationsatellites associated with such one or more satellite positioningsystems.

In an aspect, SVs 112 may additionally or alternatively be part of oneor more non-terrestrial networks (NTNs). In an NTN, an SV 112 isconnected to an earth station (also referred to as a ground station, NTNgateway, or gateway), which in turn is connected to an element in a 5Gnetwork, such as a modified base station 102 (without a terrestrialantenna) or a network node in a 5GC. This element would in turn provideaccess to other elements in the 5G network and ultimately to entitiesexternal to the 5G network, such as Internet web servers and other userdevices. In that way, a UE 104 may receive communication signals (e.g.,signals 124) from an SV 112 instead of, or in addition to, communicationsignals from a terrestrial base station 102.

Leveraging the increased data rates and decreased latency of NR, amongother things, vehicle-to-everything (V2X) communication technologies arebeing implemented to support intelligent transportation systems (ITS)applications, such as wireless communications between vehicles(vehicle-to-vehicle (V2V)), between vehicles and the roadsideinfrastructure (vehicle-to-infrastructure (V2I)), and between vehiclesand pedestrians (vehicle-to-pedestrian (V2P)). The goal is for vehiclesto be able to sense the environment around them and communicate thatinformation to other vehicles, infrastructure, and personal mobiledevices. Such vehicle communication will enable safety, mobility, andenvironmental advancements that current technologies are unable toprovide. Once fully implemented, the technology is expected to reduceunimpaired vehicle crashes by 80%.

Still referring to FIG. 1 , the wireless communications system 100 mayinclude multiple V-UEs 160 that may communicate with base stations 102over communication links 120 (e.g., using the Uu interface). V-UEs 160may also communicate directly with each other over a wireless sidelink162, with a roadside access point 164 (also referred to as a “roadsideunit”) over a wireless sidelink 166, or with UEs 104 over a wirelesssidelink 168. A wireless sidelink (or just “sidelink”) is an adaptationof the core cellular (e.g., LTE, NR) standard that allows directcommunication between two or more UEs without the communication needingto go through a base station. Sidelink communication may be unicast ormulticast, and may be used for device-to-device (D2D) media-sharing, V2Vcommunication, V2X communication (e.g., cellular V2X (cV2X)communication, enhanced V2X (eV2X) communication, etc.), emergencyrescue applications, etc. One or more of a group of V-UEs 160 utilizingsidelink communications may be within the geographic coverage area 110of a base station 102. Other V-UEs 160 in such a group may be outsidethe geographic coverage area 110 of a base station 102 or be otherwiseunable to receive transmissions from a base station 102. In some cases,groups of V-UEs 160 communicating via sidelink communications mayutilize a one-to-many (1:M) system in which each V-UE 160 transmits toevery other V-UE 160 in the group. In some cases, a base station 102facilitates the scheduling of resources for sidelink communications. Inother cases, sidelink communications are carried out between V-UEs 160without the involvement of a base station 102.

In an aspect, the sidelinks 162, 166, 168 may operate over a wirelesscommunication medium of interest, which may be shared with otherwireless communications between other vehicles and/or infrastructureaccess points, as well as other RATs. A “medium” may be composed of oneor more time, frequency, and/or space communication resources (e.g.,encompassing one or more channels across one or more carriers)associated with wireless communication between one or moretransmitter/receiver pairs.

In an aspect, the sidelinks 162, 166, 168 may be cV2X links. A firstgeneration of cV2X has been standardized in LTE, and the next generationis expected to be defined in NR. cV2X is a cellular technology that alsoenables device-to-device communications. In the U.S. and Europe, cV2X isexpected to operate in the licensed ITS band in sub-6 GHz. Other bandsmay be allocated in other countries. Thus, as a particular example, themedium of interest utilized by sidelinks 162, 166, 168 may correspond toat least a portion of the licensed ITS frequency band of sub-6 GHz.However, the present disclosure is not limited to this frequency band orcellular technology.

In an aspect, the sidelinks 162, 166, 168 may be dedicated short-rangecommunications (DSRC) links. DSRC is a one-way or two-way short-range tomedium-range wireless communication protocol that uses the wirelessaccess for vehicular environments (WAVE) protocol, also known as IEEE802.11p, for V2V, V2I, and V2P communications. IEEE 802.11p is anapproved amendment to the IEEE 802.11 standard and operates in thelicensed ITS band of 5.9 GHz (5.85-5.925 GHz) in the U.S. In Europe,IEEE 802.11p operates in the ITS G5A band (5.875-5.905 MHz). Other bandsmay be allocated in other countries. The V2V communications brieflydescribed above occur on the Safety Channel, which in the U.S. istypically a 10 MHz channel that is dedicated to the purpose of safety.The remainder of the DSRC band (the total bandwidth is 75 MHz) isintended for other services of interest to drivers, such as road rules,tolling, parking automation, etc. Thus, as a particular example, themediums of interest utilized by sidelinks 162, 166, 168 may correspondto at least a portion of the licensed ITS frequency band of 5.9 GHz.

Alternatively, the medium of interest may correspond to at least aportion of an unlicensed frequency band shared among various RATs.Although different licensed frequency bands have been reserved forcertain communication systems (e.g., by a government entity such as theFederal Communications Commission (FCC) in the United States), thesesystems, in particular those employing small cell access points, haverecently extended operation into unlicensed frequency bands such as theUnlicensed National Information Infrastructure (U-NII) band used bywireless local area network (WLAN) technologies, most notably IEEE802.11x WLAN technologies generally referred to as “Wi-Fi.” Examplesystems of this type include different variants of CDMA systems, TDMAsystems, FDMA systems, orthogonal FDMA (OFDMA) systems, single-carrierFDMA (SC-FDMA) systems, and so on.

Communications between the V-UEs 160 are referred to as V2Vcommunications, communications between the V-UEs 160 and the one or moreroadside access points 164 are referred to as V2I communications, andcommunications between the V-UEs 160 and one or more UEs 104 (where theUEs 104 are P-UEs) are referred to as V2P communications. The V2Vcommunications between V-UEs 160 may include, for example, informationabout the position, speed, acceleration, heading, and other vehicle dataof the V-UEs 160. The V2I information received at a V-UE 160 from theone or more roadside access points 164 may include, for example, roadrules, parking automation information, etc. The V2P communicationsbetween a V-UE 160 and a UE 104 may include information about, forexample, the position, speed, acceleration, and heading of the V-UE 160and the position, speed (e.g., where the UE 104 is carried by a user ona bicycle), and heading of the UE 104.

Note that although FIG. 1 only illustrates two of the UEs as V-UEs(V-UEs 160), any of the illustrated UEs (e.g., UEs 104, 152, 182, 190)may be V-UEs. In addition, while only the V-UEs 160 and a single UE 104have been illustrated as being connected over a sidelink, any of the UEsillustrated in FIG. 1 , whether V-UEs, P-UEs, etc., may be capable ofsidelink communication. Further, although only UE 182 was described asbeing capable of beam forming, any of the illustrated UEs, includingV-UEs 160, may be capable of beam forming. Where V-UEs 160 are capableof beam forming, they may beam form towards each other (i.e., towardsother V-UEs 160), towards roadside access points 164, towards other UEs(e.g., UEs 104, 152, 182, 190), etc. Thus, in some cases, V-UEs 160 mayutilize beamforming over sidelinks 162, 166, and 168.

The wireless communications system 100 may further include one or moreUEs, such as UE 190, that connects indirectly to one or morecommunication networks via one or more device-to-device (D2D)peer-to-peer (P2P) links. In the example of FIG. 1 , UE 190 has a D2DP2P link 192 with one of the UEs 104 connected to one of the basestations 102 (e.g., through which UE 190 may indirectly obtain cellularconnectivity) and a D2D P2P link 194 with WLAN STA 152 connected to theWLAN AP 150 (through which UE 190 may indirectly obtain WLAN-basedInternet connectivity). In an example, the D2D P2P links 192 and 194 maybe supported with any well-known D2D RAT, such as LTE Direct (LTE-D),WiFi Direct (WiFi-D), Bluetooth®, and so on. As another example, the D2DP2P links 192 and 194 may be sidelinks, as described above withreference to sidelinks 162, 166, and 168.

FIG. 2A illustrates an example wireless network structure 200. Forexample, a 5GC 210 (also referred to as a Next Generation Core (NGC))can be viewed functionally as control plane (C-plane) functions 214(e.g., UE registration, authentication, network access, gatewayselection, etc.) and user plane (U-plane) functions 212, (e.g., UEgateway function, access to data networks, IP routing, etc.) whichoperate cooperatively to form the core network. User plane interface(NG-U) 213 and control plane interface (NG-C) 215 connect the gNB 222 tothe 5GC 210 and specifically to the user plane functions 212 and controlplane functions 214, respectively. In an additional configuration, anng-eNB 224 may also be connected to the 5GC 210 via NG-C 215 to thecontrol plane functions 214 and NG-U 213 to user plane functions 212.Further, ng-eNB 224 may directly communicate with gNB 222 via a backhaulconnection 223. In some configurations, a Next Generation RAN (NG-RAN)220 may have one or more gNB s 222, while other configurations includeone or more of both ng-eNB s 224 and gNB s 222. Either (or both) gNB 222or ng-eNB 224 may communicate with one or more UEs 204 (e.g., any of theUEs described herein).

Another optional aspect may include a location server 230, which may bein communication with the 5GC 210 to provide location assistance forUE(s) 204. The location server 230 can be implemented as a plurality ofseparate servers (e.g., physically separate servers, different softwaremodules on a single server, different software modules spread acrossmultiple physical servers, etc.), or alternately may each correspond toa single server. The location server 230 can be configured to supportone or more location services for UEs 204 that can connect to thelocation server 230 via the core network, 5GC 210, and/or via theInternet (not illustrated). Further, the location server 230 may beintegrated into a component of the core network, or alternatively may beexternal to the core network (e.g., a third party server, such as anoriginal equipment manufacturer (OEM) server or service server).

FIG. 2B illustrates another example wireless network structure 250. A5GC 260 (which may correspond to 5GC 210 in FIG. 2A) can be viewedfunctionally as control plane functions, provided by an access andmobility management function (AMF) 264, and user plane functions,provided by a user plane function (UPF) 262, which operate cooperativelyto form the core network (i.e., 5GC 260). The functions of the AMF 264include registration management, connection management, reachabilitymanagement, mobility management, lawful interception, transport forsession management (SM) messages between one or more UEs 204 (e.g., anyof the UEs described herein) and a session management function (SMF)266, transparent proxy services for routing SM messages, accessauthentication and access authorization, transport for short messageservice (SMS) messages between the UE 204 and the short message servicefunction (SMSF) (not shown), and security anchor functionality (SEAF).The AMF 264 also interacts with an authentication server function (AUSF)(not shown) and the UE 204, and receives the intermediate key that wasestablished as a result of the UE 204 authentication process. In thecase of authentication based on a UMTS (universal mobiletelecommunications system) subscriber identity module (USIM), the AMF264 retrieves the security material from the AUSF. The functions of theAMF 264 also include security context management (SCM). The SCM receivesa key from the SEAF that it uses to derive access-network specific keys.The functionality of the AMF 264 also includes location servicesmanagement for regulatory services, transport for location servicesmessages between the UE 204 and a location management function (LMF) 270(which acts as a location server 230), transport for location servicesmessages between the NG-RAN 220 and the LMF 270, evolved packet system(EPS) bearer identifier allocation for interworking with the EPS, and UE204 mobility event notification. In addition, the AMF 264 also supportsfunctionalities for non-3GPP (Third Generation Partnership Project)access networks.

Functions of the UPF 262 include acting as an anchor point forintra-/inter-RAT mobility (when applicable), acting as an externalprotocol data unit (PDU) session point of interconnect to a data network(not shown), providing packet routing and forwarding, packet inspection,user plane policy rule enforcement (e.g., gating, redirection, trafficsteering), lawful interception (user plane collection), traffic usagereporting, quality of service (QoS) handling for the user plane (e.g.,uplink/downlink rate enforcement, reflective QoS marking in thedownlink), uplink traffic verification (service data flow (SDF) to QoSflow mapping), transport level packet marking in the uplink anddownlink, downlink packet buffering and downlink data notificationtriggering, and sending and forwarding of one or more “end markers” tothe source RAN node. The UPF 262 may also support transfer of locationservices messages over a user plane between the UE 204 and a locationserver, such as an SLP 272.

The functions of the SMF 266 include session management, UE Internetprotocol (IP) address allocation and management, selection and controlof user plane functions, configuration of traffic steering at the UPF262 to route traffic to the proper destination, control of part ofpolicy enforcement and QoS, and downlink data notification. Theinterface over which the SMF 266 communicates with the AMF 264 isreferred to as the N11 interface.

Another optional aspect may include an LMF 270, which may be incommunication with the 5GC 260 to provide location assistance for UEs204. The LMF 270 can be implemented as a plurality of separate servers(e.g., physically separate servers, different software modules on asingle server, different software modules spread across multiplephysical servers, etc.), or alternately may each correspond to a singleserver. The LMF 270 can be configured to support one or more locationservices for UEs 204 that can connect to the LMF 270 via the corenetwork, 5GC 260, and/or via the Internet (not illustrated). The SLP 272may support similar functions to the LMF 270, but whereas the LMF 270may communicate with the AMF 264, NG-RAN 220, and UEs 204 over a controlplane (e.g., using interfaces and protocols intended to convey signalingmessages and not voice or data), the SLP 272 may communicate with UEs204 and external clients (not shown in FIG. 2B) over a user plane (e.g.,using protocols intended to carry voice and/or data like thetransmission control protocol (TCP) and/or IP).

User plane interface 263 and control plane interface 265 connect the 5GC260, and specifically the UPF 262 and AMF 264, respectively, to one ormore gNBs 222 and/or ng-eNBs 224 in the NG-RAN 220. The interfacebetween gNB(s) 222 and/or ng-eNB(s) 224 and the AMF 264 is referred toas the “N2” interface, and the interface between gNB(s) 222 and/orng-eNB(s) 224 and the UPF 262 is referred to as the “N3” interface. ThegNB(s) 222 and/or ng-eNB(s) 224 of the NG-RAN 220 may communicatedirectly with each other via backhaul connections 223, referred to asthe “Xn-C” interface. One or more of gNBs 222 and/or ng-eNBs 224 maycommunicate with one or more UEs 204 over a wireless interface, referredto as the “Uu” interface.

The functionality of a gNB 222 is divided between a gNB central unit(gNB-CU) 226 and one or more gNB distributed units (gNB-DUs) 228. Theinterface 232 between the gNB-CU 226 and the one or more gNB-DUs 228 isreferred to as the “F1” interface. A gNB-CU 226 is a logical node thatincludes the base station functions of transferring user data, mobilitycontrol, radio access network sharing, positioning, session management,and the like, except for those functions allocated exclusively to thegNB-DU(s) 228. More specifically, the gNB-CU 226 hosts the radioresource control (RRC), service data adaptation protocol (SDAP), andpacket data convergence protocol (PDCP) protocols of the gNB 222. AgNB-DU 228 is a logical node that hosts the radio link control (RLC),medium access control (MAC), and physical (PHY) layers of the gNB 222.Its operation is controlled by the gNB-CU 226. One gNB-DU 228 cansupport one or more cells, and one cell is supported by only one gNB-DU228. Thus, a UE 204 communicates with the gNB-CU 226 via the RRC, SDAP,and PDCP layers and with a gNB-DU 228 via the RLC, MAC, and PHY layers.

FIGS. 3A, 3B, and 3C illustrate several example components (representedby corresponding blocks) that may be incorporated into a UE 302 (whichmay correspond to any of the UEs described herein), a base station 304(which may correspond to any of the base stations described herein), anda network entity 306 (which may correspond to or embody any of thenetwork functions described herein, including the location server 230and the LMF 270, or alternatively may be independent from the NG-RAN 220and/or 5GC 210/260 infrastructure depicted in FIGS. 2A and 2B, such as aprivate network) to support the file transmission operations as taughtherein. It will be appreciated that these components may be implementedin different types of apparatuses in different implementations (e.g., inan ASIC, in a system-on-chip (SoC), etc.). The illustrated componentsmay also be incorporated into other apparatuses in a communicationsystem. For example, other apparatuses in a system may includecomponents similar to those described to provide similar functionality.Also, a given apparatus may contain one or more of the components. Forexample, an apparatus may include multiple transceiver components thatenable the apparatus to operate on multiple carriers and/or communicatevia different technologies.

The UE 302 and the base station 304 each include one or more wirelesswide area network (WWAN) transceivers 310 and 350, respectively,providing means for communicating (e.g., means for transmitting, meansfor receiving, means for measuring, means for tuning, means forrefraining from transmitting, etc.) via one or more wirelesscommunication networks (not shown), such as an NR network, an LTEnetwork, a GSM network, and/or the like. The WWAN transceivers 310 and350 may each be connected to one or more antennas 316 and 356,respectively, for communicating with other network nodes, such as otherUEs, access points, base stations (e.g., eNBs, gNBs), etc., via at leastone designated RAT (e.g., NR, LTE, GSM, etc.) over a wirelesscommunication medium of interest (e.g., some set of time/frequencyresources in a particular frequency spectrum). The WWAN transceivers 310and 350 may be variously configured for transmitting and encodingsignals 318 and 358 (e.g., messages, indications, information, and soon), respectively, and, conversely, for receiving and decoding signals318 and 358 (e.g., messages, indications, information, pilots, and soon), respectively, in accordance with the designated RAT. Specifically,the WWAN transceivers 310 and 350 include one or more transmitters 314and 354, respectively, for transmitting and encoding signals 318 and358, respectively, and one or more receivers 312 and 352, respectively,for receiving and decoding signals 318 and 358, respectively.

The UE 302 and the base station 304 each also include, at least in somecases, one or more short-range wireless transceivers 320 and 360,respectively. The short-range wireless transceivers 320 and 360 may beconnected to one or more antennas 326 and 366, respectively, and providemeans for communicating (e.g., means for transmitting, means forreceiving, means for measuring, means for tuning, means for refrainingfrom transmitting, etc.) with other network nodes, such as other UEs,access points, base stations, etc., via at least one designated RAT(e.g., WiFi, LTE-D, Bluetooth®, Zigbee®, Z-Wave®, PC5, dedicatedshort-range communications (DSRC), wireless access for vehicularenvironments (WAVE), near-field communication (NFC), etc.) over awireless communication medium of interest. The short-range wirelesstransceivers 320 and 360 may be variously configured for transmittingand encoding signals 328 and 368 (e.g., messages, indications,information, and so on), respectively, and, conversely, for receivingand decoding signals 328 and 368 (e.g., messages, indications,information, pilots, and so on), respectively, in accordance with thedesignated RAT. Specifically, the short-range wireless transceivers 320and 360 include one or more transmitters 324 and 364, respectively, fortransmitting and encoding signals 328 and 368, respectively, and one ormore receivers 322 and 362, respectively, for receiving and decodingsignals 328 and 368, respectively. As specific examples, the short-rangewireless transceivers 320 and 360 may be WiFi transceivers, Bluetooth®transceivers, Zigbee® and/or Z-Wave® transceivers, NFC transceivers, orvehicle-to-vehicle (V2V) and/or vehicle-to-everything (V2X)transceivers.

The UE 302 and the base station 304 also include, at least in somecases, satellite signal receivers 330 and 370. The satellite signalreceivers 330 and 370 may be connected to one or more antennas 336 and376, respectively, and may provide means for receiving and/or measuringsatellite positioning/communication signals 338 and 378, respectively.Where the satellite signal receivers 330 and 370 are satellitepositioning system receivers, the satellite positioning/communicationsignals 338 and 378 may be global positioning system (GPS) signals,global navigation satellite system (GLONASS) signals, Galileo signals,Beidou signals, Indian Regional Navigation Satellite System (NAVIC),Quasi-Zenith Satellite System (QZSS), etc. Where the satellite signalreceivers 330 and 370 are non-terrestrial network (NTN) receivers, thesatellite positioning/communication signals 338 and 378 may becommunication signals (e.g., carrying control and/or user data)originating from a 5G network. The satellite signal receivers 330 and370 may comprise any suitable hardware and/or software for receiving andprocessing satellite positioning/communication signals 338 and 378,respectively. The satellite signal receivers 330 and 370 may requestinformation and operations as appropriate from the other systems, and,at least in some cases, perform calculations to determine locations ofthe UE 302 and the base station 304, respectively, using measurementsobtained by any suitable satellite positioning system algorithm.

The base station 304 and the network entity 306 each include one or morenetwork transceivers 380 and 390, respectively, providing means forcommunicating (e.g., means for transmitting, means for receiving, etc.)with other network entities (e.g., other base stations 304, othernetwork entities 306). For example, the base station 304 may employ theone or more network transceivers 380 to communicate with other basestations 304 or network entities 306 over one or more wired or wirelessbackhaul links. As another example, the network entity 306 may employthe one or more network transceivers 390 to communicate with one or morebase station 304 over one or more wired or wireless backhaul links, orwith other network entities 306 over one or more wired or wireless corenetwork interfaces.

A transceiver may be configured to communicate over a wired or wirelesslink. A transceiver (whether a wired transceiver or a wirelesstransceiver) includes transmitter circuitry (e.g., transmitters 314,324, 354, 364) and receiver circuitry (e.g., receivers 312, 322, 352,362). A transceiver may be an integrated device (e.g., embodyingtransmitter circuitry and receiver circuitry in a single device) in someimplementations, may comprise separate transmitter circuitry andseparate receiver circuitry in some implementations, or may be embodiedin other ways in other implementations. The transmitter circuitry andreceiver circuitry of a wired transceiver (e.g., network transceivers380 and 390 in some implementations) may be coupled to one or more wirednetwork interface ports. Wireless transmitter circuitry (e.g.,transmitters 314, 324, 354, 364) may include or be coupled to aplurality of antennas (e.g., antennas 316, 326, 356, 366), such as anantenna array, that permits the respective apparatus (e.g., UE 302, basestation 304) to perform transmit “beamforming,” as described herein.Similarly, wireless receiver circuitry (e.g., receivers 312, 322, 352,362) may include or be coupled to a plurality of antennas (e.g.,antennas 316, 326, 356, 366), such as an antenna array, that permits therespective apparatus (e.g., UE 302, base station 304) to perform receivebeamforming, as described herein. In an aspect, the transmittercircuitry and receiver circuitry may share the same plurality ofantennas (e.g., antennas 316, 326, 356, 366), such that the respectiveapparatus can only receive or transmit at a given time, not both at thesame time. A wireless transceiver (e.g., WWAN transceivers 310 and 350,short-range wireless transceivers 320 and 360) may also include anetwork listen module (NLM) or the like for performing variousmeasurements.

As used herein, the various wireless transceivers (e.g., transceivers310, 320, 350, and 360, and network transceivers 380 and 390 in someimplementations) and wired transceivers (e.g., network transceivers 380and 390 in some implementations) may generally be characterized as “atransceiver,” “at least one transceiver,” or “one or more transceivers.”As such, whether a particular transceiver is a wired or wirelesstransceiver may be inferred from the type of communication performed.For example, backhaul communication between network devices or serverswill generally relate to signaling via a wired transceiver, whereaswireless communication between a UE (e.g., UE 302) and a base station(e.g., base station 304) will generally relate to signaling via awireless transceiver.

The UE 302, the base station 304, and the network entity 306 alsoinclude other components that may be used in conjunction with theoperations as disclosed herein. The UE 302, the base station 304, andthe network entity 306 include one or more processors 332, 384, and 394,respectively, for providing functionality relating to, for example,wireless communication, and for providing other processingfunctionality. The processors 332, 384, and 394 may therefore providemeans for processing, such as means for determining, means forcalculating, means for receiving, means for transmitting, means forindicating, etc. In an aspect, the processors 332, 384, and 394 mayinclude, for example, one or more general purpose processors, multi-coreprocessors, central processing units (CPUs), ASICs, digital signalprocessors (DSPs), field programmable gate arrays (FPGAs), otherprogrammable logic devices or processing circuitry, or variouscombinations thereof.

The UE 302, the base station 304, and the network entity 306 includememory circuitry implementing memories 340, 386, and 396 (e.g., eachincluding a memory device), respectively, for maintaining information(e.g., information indicative of reserved resources, thresholds,parameters, and so on). The memories 340, 386, and 396 may thereforeprovide means for storing, means for retrieving, means for maintaining,etc. In some cases, the UE 302, the base station 304, and the networkentity 306 may include Discovery component 342, 388, and 398,respectively. The Discovery component 342, 388, and 398 may be hardwarecircuits that are part of or coupled to the processors 332, 384, and394, respectively, that, when executed, cause the UE 302, the basestation 304, and the network entity 306 to perform the functionalitydescribed herein. In other aspects, the Discovery component 342, 388,and 398 may be external to the processors 332, 384, and 394 (e.g., partof a modem processing system, integrated with another processing system,etc.). Alternatively, the Discovery component 342, 388, and 398 may bememory modules stored in the memories 340, 386, and 396, respectively,that, when executed by the processors 332, 384, and 394 (or a modemprocessing system, another processing system, etc.), cause the UE 302,the base station 304, and the network entity 306 to perform thefunctionality described herein. FIG. 3A illustrates possible locationsof the Discovery component 342, which may be, for example, part of theone or more WWAN transceivers 310, the memory 340, the one or moreprocessors 332, or any combination thereof, or may be a standalonecomponent. FIG. 3B illustrates possible locations of the Discoverycomponent 388, which may be, for example, part of the one or more WWANtransceivers 350, the memory 386, the one or more processors 384, or anycombination thereof, or may be a standalone component. FIG. 3Cillustrates possible locations of the Discovery component 398, which maybe, for example, part of the one or more network transceivers 390, thememory 396, the one or more processors 394, or any combination thereof,or may be a standalone component.

The UE 302 may include one or more sensors 344 coupled to the one ormore processors 332 to provide means for sensing or detecting movementand/or orientation information that is independent of motion dataderived from signals received by the one or more WWAN transceivers 310,the one or more short-range wireless transceivers 320, and/or thesatellite signal receiver 330. By way of example, the sensor(s) 344 mayinclude an accelerometer (e.g., a micro-electrical mechanical systems(MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), analtimeter (e.g., a barometric pressure altimeter), and/or any other typeof movement detection sensor. Moreover, the sensor(s) 344 may include aplurality of different types of devices and combine their outputs inorder to provide motion information. For example, the sensor(s) 344 mayuse a combination of a multi-axis accelerometer and orientation sensorsto provide the ability to compute positions in two-dimensional (2D)and/or three-dimensional (3D) coordinate systems.

In addition, the UE 302 includes a user interface 346 providing meansfor providing indications (e.g., audible and/or visual indications) to auser and/or for receiving user input (e.g., upon user actuation of asensing device such a keypad, a touch screen, a microphone, and so on).Although not shown, the base station 304 and the network entity 306 mayalso include user interfaces.

Referring to the one or more processors 384 in more detail, in thedownlink, IP packets from the network entity 306 may be provided to theprocessor 384. The one or more processors 384 may implementfunctionality for an RRC layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The one or more processors 384 may provide RRClayer functionality associated with broadcasting of system information(e.g., master information block (MIB), system information blocks(SIBs)), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter-RAT mobility, and measurement configurationfor UE measurement reporting; PDCP layer functionality associated withheader compression/decompression, security (ciphering, deciphering,integrity protection, integrity verification), and handover supportfunctions; RLC layer functionality associated with the transfer of upperlayer PDUs, error correction through automatic repeat request (ARQ),concatenation, segmentation, and reassembly of RLC service data units(SDUs), re-segmentation of RLC data PDUs, and reordering of RLC dataPDUs; and MAC layer functionality associated with mapping betweenlogical channels and transport channels, scheduling informationreporting, error correction, priority handling, and logical channelprioritization.

The transmitter 354 and the receiver 352 may implement Layer-1 (L1)functionality associated with various signal processing functions.Layer-1, which includes a physical (PHY) layer, may include errordetection on the transport channels, forward error correction (FEC)coding/decoding of the transport channels, interleaving, rate matching,mapping onto physical channels, modulation/demodulation of physicalchannels, and MIMO antenna processing. The transmitter 354 handlesmapping to signal constellations based on various modulation schemes(e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an orthogonalfrequency division multiplexing (OFDM) subcarrier, multiplexed with areference signal (e.g., pilot) in the time and/or frequency domain, andthen combined together using an inverse fast Fourier transform (IFFT) toproduce a physical channel carrying a time domain OFDM symbol stream.The OFDM symbol stream is spatially precoded to produce multiple spatialstreams. Channel estimates from a channel estimator may be used todetermine the coding and modulation scheme, as well as for spatialprocessing. The channel estimate may be derived from a reference signaland/or channel condition feedback transmitted by the UE 302. Eachspatial stream may then be provided to one or more different antennas356. The transmitter 354 may modulate an RF carrier with a respectivespatial stream for transmission.

At the UE 302, the receiver 312 receives a signal through its respectiveantenna(s) 316. The receiver 312 recovers information modulated onto anRF carrier and provides the information to the one or more processors332. The transmitter 314 and the receiver 312 implement Layer-1functionality associated with various signal processing functions. Thereceiver 312 may perform spatial processing on the information torecover any spatial streams destined for the UE 302. If multiple spatialstreams are destined for the UE 302, they may be combined by thereceiver 312 into a single OFDM symbol stream. The receiver 312 thenconverts the OFDM symbol stream from the time-domain to the frequencydomain using a fast Fourier transform (FFT). The frequency domain signalcomprises a separate OFDM symbol stream for each subcarrier of the OFDMsignal. The symbols on each subcarrier, and the reference signal, arerecovered and demodulated by determining the most likely signalconstellation points transmitted by the base station 304. These softdecisions may be based on channel estimates computed by a channelestimator. The soft decisions are then decoded and de-interleaved torecover the data and control signals that were originally transmitted bythe base station 304 on the physical channel. The data and controlsignals are then provided to the one or more processors 332, whichimplements Layer-3 (L3) and Layer-2 (L2) functionality.

In the uplink, the one or more processors 332 provides demultiplexingbetween transport and logical channels, packet reassembly, deciphering,header decompression, and control signal processing to recover IPpackets from the core network. The one or more processors 332 are alsoresponsible for error detection.

Similar to the functionality described in connection with the downlinktransmission by the base station 304, the one or more processors 332provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto transport blocks(TB s), demultiplexing of MAC SDUs from TB s, scheduling informationreporting, error correction through hybrid automatic repeat request(HARQ), priority handling, and logical channel prioritization.

Channel estimates derived by the channel estimator from a referencesignal or feedback transmitted by the base station 304 may be used bythe transmitter 314 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the transmitter 314 may be provided to different antenna(s)316. The transmitter 314 may modulate an RF carrier with a respectivespatial stream for transmission.

The uplink transmission is processed at the base station 304 in a mannersimilar to that described in connection with the receiver function atthe UE 302. The receiver 352 receives a signal through its respectiveantenna(s) 356. The receiver 352 recovers information modulated onto anRF carrier and provides the information to the one or more processors384.

In the uplink, the one or more processors 384 provides demultiplexingbetween transport and logical channels, packet reassembly, deciphering,header decompression, control signal processing to recover IP packetsfrom the UE 302. IP packets from the one or more processors 384 may beprovided to the core network. The one or more processors 384 are alsoresponsible for error detection.

For convenience, the UE 302, the base station 304, and/or the networkentity 306 are shown in FIGS. 3A, 3B, and 3C as including variouscomponents that may be configured according to the various examplesdescribed herein. It will be appreciated, however, that the illustratedcomponents may have different functionality in different designs. Inparticular, various components in FIGS. 3A to 3C are optional inalternative configurations and the various aspects includeconfigurations that may vary due to design choice, costs, use of thedevice, or other considerations. For example, in case of FIG. 3A, aparticular implementation of UE 302 may omit the WWAN transceiver(s) 310(e.g., a wearable device or tablet computer or PC or laptop may haveWi-Fi and/or Bluetooth capability without cellular capability), or mayomit the short-range wireless transceiver(s) 320 (e.g., cellular-only,etc.), or may omit the satellite signal receiver 330, or may omit thesensor(s) 344, and so on. In another example, in case of FIG. 3B, aparticular implementation of the base station 304 may omit the WWANtransceiver(s) 350 (e.g., a Wi-Fi “hotspot” access point withoutcellular capability), or may omit the short-range wirelesstransceiver(s) 360 (e.g., cellular-only, etc.), or may omit thesatellite receiver 370, and so on. For brevity, illustration of thevarious alternative configurations is not provided herein, but would bereadily understandable to one skilled in the art.

The various components of the UE 302, the base station 304, and thenetwork entity 306 may be communicatively coupled to each other overdata buses 334, 382, and 392, respectively. In an aspect, the data buses334, 382, and 392 may form, or be part of, a communication interface ofthe UE 302, the base station 304, and the network entity 306,respectively. For example, where different logical entities are embodiedin the same device (e.g., gNB and location server functionalityincorporated into the same base station 304), the data buses 334, 382,and 392 may provide communication between them.

The components of FIGS. 3A, 3B, and 3C may be implemented in variousways. In some implementations, the components of FIGS. 3A, 3B, and 3Cmay be implemented in one or more circuits such as, for example, one ormore processors and/or one or more ASICs (which may include one or moreprocessors). Here, each circuit may use and/or incorporate at least onememory component for storing information or executable code used by thecircuit to provide this functionality. For example, some or all of thefunctionality represented by blocks 310 to 346 may be implemented byprocessor and memory component(s) of the UE 302 (e.g., by execution ofappropriate code and/or by appropriate configuration of processorcomponents). Similarly, some or all of the functionality represented byblocks 350 to 388 may be implemented by processor and memorycomponent(s) of the base station 304 (e.g., by execution of appropriatecode and/or by appropriate configuration of processor components). Also,some or all of the functionality represented by blocks 390 to 398 may beimplemented by processor and memory component(s) of the network entity306 (e.g., by execution of appropriate code and/or by appropriateconfiguration of processor components). For simplicity, variousoperations, acts, and/or functions are described herein as beingperformed “by a UE,” “by a base station,” “by a network entity,” etc.However, as will be appreciated, such operations, acts, and/or functionsmay actually be performed by specific components or combinations ofcomponents of the UE 302, base station 304, network entity 306, etc.,such as the processors 332, 384, 394, the transceivers 310, 320, 350,and 360, the memories 340, 386, and 396, the Discovery component 342,388, and 398, etc.

In some designs, the network entity 306 may be implemented as a corenetwork component. In other designs, the network entity 306 may bedistinct from a network operator or operation of the cellular networkinfrastructure (e.g., NG RAN 220 and/or 5GC 210/260). For example, thenetwork entity 306 may be a component of a private network that may beconfigured to communicate with the UE 302 via the base station 304 orindependently from the base station 304 (e.g., over a non-cellularcommunication link, such as WiFi).

FIG. 4 is a block diagram illustrating various components of an exampleUE 400, according to aspects of the disclosure. In an aspect, the UE 400may correspond to any of the UEs described herein. As a specificexample, the UE 400 may be a V-UE, such as V-UE 160 in FIG. 1 . For thesake of simplicity, the various features and functions illustrated inthe block diagram of FIG. 4 are connected together using a common databus that is meant to represent that these various features and functionsare operatively coupled together. Those skilled in the art willrecognize that other connections, mechanisms, features, functions, orthe like, may be provided and adapted as necessary to operatively coupleand configure an actual UE. Further, it is also recognized that one ormore of the features or functions illustrated in the example of FIG. 4may be further subdivided, or two or more of the features or functionsillustrated in FIG. 4 may be combined.

The UE 400 may include at least one transceiver 404 connected to one ormore antennas 402 and providing means for communicating (e.g., means fortransmitting, means for receiving, means for measuring, means fortuning, means for refraining from transmitting, etc.) with other networknodes, such as V-UEs (e.g., V-UEs 160), infrastructure access points(e.g., roadside access point 164), P-UEs (e.g., UEs 104), base stations(e.g., base stations 102), etc., via at least one designated RAT (e.g.,cV2X or IEEE 802.11p) over one or more communication links (e.g.,communication links 120, sidelinks 162, 166, 168, mmW communication link184). The at least one transceiver 404 may be variously configured fortransmitting and encoding signals (e.g., messages, indications,information, and so on), and, conversely, for receiving and decodingsignals (e.g., messages, indications, information, pilots, and so on) inaccordance with the designated RAT. In an aspect, the at least onetransceiver 404 and the antenna(s) 402 may form a (wireless)communication interface of the UE 400.

As used herein, a “transceiver” may include at least one transmitter andat least one receiver in an integrated device (e.g., embodied as atransmitter circuit and a receiver circuit of a single communicationdevice) in some implementations, may comprise a separate transmitterdevice and a separate receiver device in some implementations, or may beembodied in other ways in other implementations. In an aspect, atransmitter may include or be coupled to a plurality of antennas (e.g.,antenna(s) 402), such as an antenna array, that permits the UE 400 toperform transmit “beamforming,” as described herein. Similarly, areceiver may include or be coupled to a plurality of antennas (e.g.,antenna(s) 402), such as an antenna array, that permits the UE 400 toperform receive beamforming, as described herein. In an aspect, thetransmitter(s) and receiver(s) may share the same plurality of antennas(e.g., antenna(s) 402), such that the UE 400 can only receive ortransmit at a given time, not both at the same time. In some cases, atransceiver may not provide both transmit and receive functionalities.For example, a low functionality receiver circuit may be employed insome designs to reduce costs when providing full communication is notnecessary (e.g., a receiver chip or similar circuitry simply providinglow-level sniffing).

The UE 400 may also include a satellite positioning service (SPS)receiver 406. The SPS receiver 406 may be connected to the one or moreantennas 402 and may provide means for receiving and/or measuringsatellite signals. The SPS receiver 406 may comprise any suitablehardware and/or software for receiving and processing SPS signals, suchas global positioning system (GPS) signals. The SPS receiver 406requests information and operations as appropriate from the othersystems, and performs the calculations necessary to determine the UE's400 position using measurements obtained by any suitable SPS algorithm.

One or more sensors 408 may be coupled to at least one processor 410 andmay provide means for sensing or detecting information related to thestate and/or environment of the UE 400, such as speed, heading (e.g.,compass heading), headlight status, gas mileage, etc. By way of example,the one or more sensors 408 may include a speedometer, a tachometer, anaccelerometer (e.g., a microelectromechanical systems (MEMS) device), agyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., abarometric pressure altimeter), etc.

The at least one processor 410 may include one or more centralprocessing units (CPUs), microprocessors, microcontrollers, ASICs,processing cores, digital signal processors (DSPs), field-programmablegate arrays (FPGAs), or the like that provide processing functions, aswell as other calculation and control functionality. The at least oneprocessor 410 may therefore provide means for processing, such as meansfor determining, means for calculating, means for receiving, means fortransmitting, means for indicating, etc. The at least one processor 410may include any form of logic suitable for performing, or causing thecomponents of the UE 400 to perform, at least the techniques describedherein.

The at least one processor 410 may also be coupled to a memory 414providing means for storing (including means for retrieving, means formaintaining, etc.) data and software instructions for executingprogrammed functionality within the UE 400. The memory 414 may beon-board the at least one processor 410 (e.g., within the sameintegrated circuit (IC) package), and/or the memory 414 may be externalto the at least one processor 410 and functionally coupled over a databus.

The UE 400 may include a user interface 450 that provides any suitableinterface systems, such as a microphone/speaker 452, keypad 454, anddisplay 456 that allow user interaction with the UE 400. Themicrophone/speaker 452 may provide for voice communication services withthe UE 400. The keypad 454 may comprise any suitable buttons for userinput to the UE 400. The display 456 may comprise any suitable display,such as, for example, a backlit liquid crystal display (LCD), and mayfurther include a touch screen display for additional user input modes.The user interface 450 may therefore be a means for providingindications (e.g., audible and/or visual indications) to a user and/orfor receiving user input (e.g., via user actuation of a sensing devicesuch a keypad, a touch screen, a microphone, and so on).

In an aspect, the UE 400 may include a sidelink manager 470 coupled tothe at least one processor 410. The sidelink manager 470 may be ahardware, software, or firmware component that, when executed, causesthe UE 400 to perform the operations described herein. For example, thesidelink manager 470 may be a software module stored in memory 414 andexecutable by the at least one processor 410. As another example, thesidelink manager 470 may be a hardware circuit (e.g., an ASIC, afield-programmable gate array (FPGA), etc.) within the UE 400.

FIG. 5 illustrates an example of a wireless communications system 500that supports wireless unicast sidelink establishment, according toaspects of the disclosure. In some examples, wireless communicationssystem 500 may implement aspects of wireless communications systems 100,200, and 250. Wireless communications system 500 may include a first UE502 and a second UE 504, which may be examples of any of the UEsdescribed herein. As specific examples, UEs 502 and 504 may correspondto V-UEs 160 in FIG. 1 , UE 190 and UE 104 in FIG. 1 connected over D2DP2P link 192, or UEs 204 in FIGS. 2A and 2B.

In the example of FIG. 5 , the UE 502 may attempt to establish a unicastconnection over a sidelink with the UE 504, which may be a V2X sidelinkbetween the UE 502 and UE 504. As specific examples, the establishedsidelink connection may correspond to sidelinks 162 and/or 168 in FIG. 1. The sidelink connection may be established in an omni-directionalfrequency range (e.g., FR1) and/or a mmW frequency range (e.g., FR2). Insome cases, the UE 502 may be referred to as an initiating UE thatinitiates the sidelink connection procedure, and the UE 504 may bereferred to as a target UE that is targeted for the sidelink connectionprocedure by the initiating UE.

For establishing the unicast connection, access stratum (AS) (afunctional layer in the UMTS and LTE protocol stacks between the RAN andthe UE that is responsible for transporting data over wireless links andmanaging radio resources, and which is part of Layer 2) parameters maybe configured and negotiated between the UE 502 and UE 504. For example,a transmission and reception capability matching may be negotiatedbetween the UE 502 and UE 504. Each UE may have different capabilities(e.g., transmission and reception, 64 quadrature amplitude modulation(QAM), transmission diversity, carrier aggregation (CA), supportedcommunications frequency band(s), etc.). In some cases, differentservices may be supported at the upper layers of corresponding protocolstacks for UE 502 and UE 504. Additionally, a security association maybe established between UE 502 and UE 504 for the unicast connection.Unicast traffic may benefit from security protection at a link level(e.g., integrity protection). Security requirements may differ fordifferent wireless communications systems. For example, V2X and Uusystems may have different security requirements (e.g., Uu security doesnot include confidentiality protection). Additionally, IP configurations(e.g., IP versions, addresses, etc.) may be negotiated for the unicastconnection between UE 502 and UE 504.

In some cases, UE 504 may create a service announcement (e.g., a servicecapability message) to transmit over a cellular network (e.g., cV2X) toassist the sidelink connection establishment. Conventionally, UE 502 mayidentify and locate candidates for sidelink communications based on abasic service message (BSM) broadcasted unencrypted by nearby UEs (e.g.,UE 504). The BSM may include location information, security and identityinformation, and vehicle information (e.g., speed, maneuver, size, etc.)for the corresponding UE. However, for different wireless communicationssystems (e.g., D2D or V2X communications), a discovery channel may notbe configured so that UE 502 is able to detect the BSM(s). Accordingly,the service announcement transmitted by UE 504 and other nearby UEs(e.g., a discovery signal) may be an upper layer signal and broadcasted(e.g., in an NR sidelink broadcast). In some cases, the UE 504 mayinclude one or more parameters for itself in the service announcement,including connection parameters and/or capabilities it possesses. The UE502 may then monitor for and receive the broadcasted serviceannouncement to identify potential UEs for corresponding sidelinkconnections. In some cases, the UE 502 may identify the potential UEsbased on the capabilities each UE indicates in their respective serviceannouncements.

The service announcement may include information to assist the UE 502(e.g., or any initiating UE) to identify the UE transmitting the serviceannouncement (UE 504 in the example of FIG. 5 ). For example, theservice announcement may include channel information where directcommunication requests may be sent. In some cases, the channelinformation may be RAT-specific (e.g., specific to LTE or NR) and mayinclude a resource pool within which UE 502 transmits the communicationrequest. Additionally, the service announcement may include a specificdestination address for the UE (e.g., a Layer 2 destination address) ifthe destination address is different from the current address (e.g., theaddress of the streaming provider or UE transmitting the serviceannouncement). The service announcement may also include a network ortransport layer for the UE 502 to transmit a communication request on.For example, the network layer (also referred to as “Layer 3” or “L3”)or the transport layer (also referred to as “Layer 4” or “L4”) mayindicate a port number of an application for the UE transmitting theservice announcement. In some cases, no IP addressing may be needed ifthe signaling (e.g., PC5 signaling) carries a protocol (e.g., areal-time transport protocol (RTP)) directly or gives alocally-generated random protocol. Additionally, the serviceannouncement may include a type of protocol for credential establishmentand QoS-related parameters.

After identifying a potential sidelink connection target (UE 504 in theexample of FIG. the initiating UE (UE 502 in the example of FIG. 5 ) maytransmit a connection request 515 to the identified target UE 504. Insome cases, the connection request 515 may be a first RRC messagetransmitted by the UE 502 to request a unicast connection with the UE504 (e.g., an “RRCDirectConnectionSetupRequest” message). For example,the unicast connection may utilize the PC5 interface for the sidelink,and the connection request 515 may be an RRC connection setup requestmessage. Additionally, the UE 502 may use a sidelink signaling radiobearer 505 to transport the connection request 515.

After receiving the connection request 515, the UE 504 may determinewhether to accept or reject the connection request 515. The UE 504 maybase this determination on a transmission/reception capability, anability to accommodate the unicast connection over the sidelink, aparticular service indicated for the unicast connection, the contents tobe transmitted over the unicast connection, or a combination thereof.For example, if the UE 502 wants to use a first RAT to transmit orreceive data, but the UE 504 does not support the first RAT, then the UE504 may reject the connection request 515. Additionally oralternatively, the UE 504 may reject the connection request 515 based onbeing unable to accommodate the unicast connection over the sidelink dueto limited radio resources, a scheduling issue, etc. Accordingly, the UE504 may transmit an indication of whether the request is accepted orrejected in a connection response 520. Similar to the UE 502 and theconnection request 515, the UE 504 may use a sidelink signaling radiobearer 510 to transport the connection response 520. Additionally, theconnection response 520 may be a second RRC message transmitted by theUE 504 in response to the connection request 515 (e.g., an“RRCDirectConnectionResponse” message).

In some cases, sidelink signaling radio bearers 505 and 510 may be thesame sidelink signaling radio bearer or may be separate sidelinksignaling radio bearers. Accordingly, a radio link control (RLC) layeracknowledged mode (AM) may be used for sidelink signaling radio bearers505 and 510. A UE that supports the unicast connection may listen on alogical channel associated with the sidelink signaling radio bearers. Insome cases, the AS layer (i.e., Layer 2) may pass information directlythrough RRC signaling (e.g., control plane) instead of a V2X layer(e.g., data plane).

If the connection response 520 indicates that the UE 504 accepted theconnection request 515, the UE 502 may then transmit a connectionestablishment 525 message on the sidelink signaling radio bearer 505 toindicate that the unicast connection setup is complete. In some cases,the connection establishment 525 may be a third RRC message (e.g., an“RRCDirectConnectionSetupComplete” message). Each of the connectionrequest 515, the connection response 520, and the connectionestablishment 525 may use a basic capability when being transported fromone UE to the other UE to enable each UE to be able to receive anddecode the corresponding transmission (e.g., the RRC messages).

Additionally, identifiers may be used for each of the connection request515, the connection response 520, and the connection establishment 525.For example, the identifiers may indicate which UE 502/504 istransmitting which message and/or for which UE 502/504 the message isintended. For physical (PHY) layer channels, the RRC signaling and anysubsequent data transmissions may use the same identifier (e.g., Layer 2IDs). However, for logical channels, the identifiers may be separate forthe RRC signaling and for the data transmissions. For example, on thelogical channels, the RRC signaling and the data transmissions may betreated differently and have different acknowledgement (ACK) feedbackmessaging. In some cases, for the RRC messaging, a physical layer ACKmay be used for ensuring the corresponding messages are transmitted andreceived properly.

One or more information elements may be included in the connectionrequest 515 and/or the connection response 520 for UE 502 and/or UE 504,respectively, to enable negotiation of corresponding AS layer parametersfor the unicast connection. For example, the UE 502 and/or UE 504 mayinclude packet data convergence protocol (PDCP) parameters in acorresponding unicast connection setup message to set a PDCP context forthe unicast connection. In some cases, the PDCP context may indicatewhether or not PDCP duplication is utilized for the unicast connection.Additionally, the UE 502 and/or UE 504 may include RLC parameters whenestablishing the unicast connection to set an RLC context for theunicast connection. For example, the RLC context may indicate whether anAM (e.g., a reordering timer (t-reordering) is used) or anunacknowledged mode (UM) is used for the RLC layer of the unicastcommunications.

Additionally, the UE 502 and/or UE 504 may include medium access control(MAC) parameters to set a MAC context for the unicast connection. Insome cases, the MAC context may enable resource selection algorithms, ahybrid automatic repeat request (HARQ) feedback scheme (e.g., ACK ornegative ACK (NACK) feedback), parameters for the HARQ feedback scheme,carrier aggregation, or a combination thereof for the unicastconnection. Additionally, the UE 502 and/or UE 504 may include PHY layerparameters when establishing the unicast connection to set a PHY layercontext for the unicast connection. For example, the PHY layer contextmay indicate a transmission format (unless transmission profiles areincluded for each UE 502/504) and a radio resource configuration (e.g.,bandwidth part (BWP), numerology, etc.) for the unicast connection.These information elements may be supported for different frequencyrange configurations (e.g., FR1 and FR2).

In some cases, a security context may also be set for the unicastconnection (e.g., after the connection establishment 525 message istransmitted). Before a security association (e.g., security context) isestablished between the UE 502 and UE 504, the sidelink signaling radiobearers 505 and 510 may not be protected. After a security associationis established, the sidelink signaling radio bearers 505 and 510 may beprotected. Accordingly, the security context may enable secure datatransmissions over the unicast connection and the sidelink signalingradio bearers 505 and 510. Additionally, IP layer parameters (e.g.,link-local IPv4 or IPv6 addresses) may also be negotiated. In somecases, the IP layer parameters may be negotiated by an upper layercontrol protocol running after RRC signaling is established (e.g., theunicast connection is established). As noted above, the UE 504 may baseits decision on whether to accept or reject the connection request 515on a particular service indicated for the unicast connection and/or thecontents to be transmitted over the unicast connection (e.g., upperlayer information). The particular service and/or contents may be alsoindicated by an upper layer control protocol running after RRC signalingis established.

After the unicast connection is established, the UE 502 and UE 504 maycommunicate using the unicast connection over a sidelink 530, wheresidelink data 535 is transmitted between the two UEs 502 and 504. Thesidelink 530 may correspond to sidelinks 162 and/or 168 in FIG. 1 . Insome cases, the sidelink data 535 may include RRC messages transmittedbetween the two UEs 502 and 504. To maintain this unicast connection onsidelink 530, UE 502 and/or UE 504 may transmit a keep alive message(e.g., “RRCDirectLinkAlive” message, a fourth RRC message, etc.). Insome cases, the keep alive message may be triggered periodically oron-demand (e.g., event-triggered). Accordingly, the triggering andtransmission of the keep alive message may be invoked by UE 502 or byboth UE 502 and UE 504. Additionally or alternatively, a MAC controlelement (CE) (e.g., defined over sidelink 530) may be used to monitorthe status of the unicast connection on sidelink 530 and maintain theconnection. When the unicast connection is no longer needed (e.g., UE502 travels far enough away from UE 504), either UE 502 and/or UE 504may start a release procedure to drop the unicast connection oversidelink 530. Accordingly, subsequent RRC messages may not betransmitted between UE 502 and UE 504 on the unicast connection.

FIG. 6 is a diagram 600 illustrating a wireless node 602 (which maycorrespond to any of the base stations described herein, oralternatively to any of the UEs described herein) in communication witha UE 604 (which may correspond to any of the UEs described herein). In ascenario where the wireless node 602 corresponds to a UE, the signalingdescribed below may be characterized as sidelink signaling.

Referring to FIG. 6 , the wireless node 602 may transmit a beamformedsignal to the UE 604 on one or more transmit beams 602 a, 602 b, 602 c,602 d, 602 e, 602 f, 602 g, 602 h, each having a beam identifier thatcan be used by the UE 604 to identify the respective beam. Where thewireless node 602 is beamforming towards the UE 604 with a single arrayof antennas (e.g., a single TRP/cell or UE), the wireless node 602 mayperform a “beam sweep” by transmitting first beam 602 a, then beam 602b, and so on until lastly transmitting beam 602 h. Alternatively, thewireless node 602 may transmit beams 602 a-602 h in some pattern, suchas beam 602 a, then beam 602 h, then beam 602 b, then beam 602 g, and soon. Where the wireless node 602 is beamforming towards the UE 604 usingmultiple arrays of antennas (e.g., multiple TRPs/cells), each antennaarray may perform a beam sweep of a subset of the beams 602 a-602 h.Alternatively, each of beams 602 a-602 h may correspond to a singleantenna or antenna array.

FIG. 6 further illustrates the paths 612 c, 612 d, 612 e, 612 f, and 612g followed by the beamformed signal transmitted on beams 602 c, 602 d,602 e, 602 f, and 602 g, respectively. Each path 612 c, 612 d, 612 e,612 f, 612 g may correspond to a single “multipath” or, due to thepropagation characteristics of radio frequency (RF) signals through theenvironment, may be comprised of a plurality (a cluster) of“multipaths.” Note that although only the paths for beams 602 c-602 gare shown, this is for simplicity, and the signal transmitted on each ofbeams 602 a-602 h will follow some path. In the example shown, the paths612 c, 612 d, 612 e, and 612 f are straight lines, while path 612 greflects off an obstacle 620 (e.g., a building, vehicle, terrainfeature, etc.).

The UE 604 may receive the beamformed signal from the wireless node 602on one or more receive beams 604 a, 604 b, 604 c, 604 d. Note that forsimplicity, the beams illustrated in FIG. 6 represent either transmitbeams or receive beams, depending on which of the wireless node 602 andthe UE 604 is transmitting and which is receiving. Thus, the UE 604 mayalso transmit a beamformed signal to the wireless node 602 on one ormore of the beams 604 a-604 d, and the wireless node 602 may receive thebeamformed signal from the UE 604 on one or more of the beams 602 a-602h.

In an aspect, the wireless node 602 and the UE 604 may perform beamtraining to align the transmit and receive beams of the wireless node602 and the UE 604. For example, depending on environmental conditionsand other factors, the wireless node 602 and the UE 604 may determinethat the best transmit and receive beams are 602 d and 604 b,respectively, or beams 602 e and 604 c, respectively. The direction ofthe best transmit beam for the wireless node 602 may or may not be thesame as the direction of the best receive beam, and likewise, thedirection of the best receive beam for the UE 604 may or may not be thesame as the direction of the best transmit beam.

In the example of FIG. 6 , if the wireless node 602 transmits referencesignals to the UE 604 on beams 602 c, 602 d, 602 e, 602 f, and 602 g,then transmit beam 602 e is best aligned with the LOS path 610, whiletransmit beams 602 c, 602 d, 602 f, and 602 g are not. As such, beam 602e is likely to have a higher received signal strength at the UE 604 thanbeams 602 c, 602 d, 602 f, and 602 g. Note that the reference signalstransmitted on some beams (e.g., beams 602 c and/or 6020 may not reachthe UE 604, or energy reaching the UE 604 from these beams may be so lowthat the energy may not be detectable or at least can be ignored.

In some designs, UE 604 can report the received signal strength, andoptionally, the associated measurement quality, of each measuredtransmit beam 602 c-602 g to the wireless node 602, or alternatively,the identity of the transmit beam having the highest received signalstrength (beam 602 e in the example of FIG. 6 ). Alternatively, in caseof sidelink, this operation can be reversed, and the wireless node 602(e.g., a UE, for a sidelink implementation of FIG. 6 ) can report thereceived signal strength, and optionally, the associated measurementquality, of each measured transmit beam 604 a-604 d to the UE 604 oralternatively, the identity of the transmit beam having the highestreceived signal strength (beam 604 b or 604 c in the example of FIG. 6).

Various proximity services (ProSe) models may be implemented for directsidelink discovery. In ProSe Model A, two roles are defined for theProSe-enabled UEs that are participating in ProSe Direct Discovery. Anannouncing UE announces certain information that could be used by UEs inproximity that have permission to discover, and a monitoring UE monitorscertain information of interest in proximity of announcing UEs. In ProSeModel A, the announcing UE broadcasts discovery messages at pre-defineddiscovery intervals and the monitoring UEs that are interested in thesemessages read and process the messages. In ProSe Model B, two roles aredefined for the ProSe-enabled UEs that are participating in ProSe directdiscovery. In particular, a discoverer UE transmits a request containingcertain information about what the discoverer UE is interested todiscover, and a discoveree UE receives the request message and canrespond with some information related to the discoverer's request.Discoverer UE sends information about other UEs that would like toreceive responses from, e.g., the information can be about a ProSeApplication Identity corresponding to a group and the members of thegroup can respond.

FIG. 7 illustrates a discovery procedure 700 in accordance with aspectsof the disclosure. Referring to FIG. 7 , UE 1 transmits upon N transmitbeams (N=3) with M repetitions (M=2) per beam across 6 total slots(M×N=2×3=6). In some designs, M=2 may be based on an expectation thatthe candidate responder UEs (e.g., UE 2) are monitoring for sidelinkdiscovery messages on two receive beams (e.g., alternating between therespective receive beams). In other words, repeating BTRS M times willensure that a responder UE with M receive beams will have a chance todetect BTRS on each of its receive beams. UE 2 receives the beamsweeping of BTRS on some or all of the N beams and selects the beamamong UE 2's M beams with correspondence to the best BTRS beam (i.e.,the selected beam is now paired with the best BTRS beam). UE 2 transmitsa BT response (e.g., preamble or message) on the selected beam. UE 1receives the BT response, and transmits a sidelink discovery message onthe N transmit beams. UE 2 receives the sidelink discovery message onthe beam corresponding to the best BTRS beam, and then transmits asidelink discovery response message on the selected beam. In otherdesigns, UE 2 may beam sweep the BT response instead of transmitting theBT response on the selected beam (e.g., if there is no correspondencebetween the BTRS and time).

Referring to FIG. 7 , in some designs, the BT response may be RACH-likeor CSI-RS-like. In some designs, the BT response includes the sidelinkdiscovery message, in which case the BT response may be transmitted overPSCCH or PSSCH. In some designs, the BT response includes a preambleonly, in which case the BT response preamble may be transmitted as astandalone transmission (e.g., similar to CSI-RS, and not part of PSCCHor PSSCH). In some designs, the sidelink discovery message may includeinformation about the corresponding BTRS and BT response sequences.

Referring to FIG. 7 , the overhead isN×M×BTRS+N×U×BT_Resp+N×DISC+V×DISC_Resp, where N is the number of Txbeams, M is the number of Rx beams, U is the number of UEs, V is thenumber of target UEs, BTRS, BT_Resp, DISC and DISC_Resp are the overheadof beam training reference signal, beam training response preamble,discovery message and discovery response message respectively.

-   -   N×M×BTRS because UE 1 sends BTRS N×M times.    -   N×U×BT_Resp because all the UEs need to respond to UE 1, and UE        1 need to receive the response from all directions.    -   N×DISC because it is likely UE 1 receives response preamble from        all directions, UE 1 sends discovery message in all directions,        especially when U is large.    -   V×DISC_Resp because the beam pair between UE 1 and UE 2 has been        established, the discovery response does not require beam        sweeping.

In some designs, sidelink-Synchronization Signal (S-SS)/physicalsidelink broadcast channel (PSBCH) block occupies 143 or 121 RBs fornormal or extended cyclic prefix, e.g.:

-   -   In the time domain, an S-SS/PSBCH block consists of N_(symb)        ^(S-SSB) OFDM symbols.    -   The number of OFDM symbols in an S-SS/PSBCH block N_(symb)        ^(S-SSB)=13 for normal cyclic prefix and N_(symb) ^(S-SSB)=11        for extended cyclic prefix. (An SS/PBCH block on Uu interface        consists of 4 OFDM symbols).    -   In the frequency domain, an S-SS/PSBCH block consists of 132        contiguous subcarriers with the subcarriers numbered in        increasing order from 0 to 131 within the sidelink S-SS/PSBCH        block.

The short PRACH preamble on Uu interface occupies 6 or 12 RBs for 60 kHzor 120 kHz subcarrier spacing (assuming 120 kHz PUSCH).

Referring to FIG. 7 , in some designs, the sidelink discovery messagemay include, e.g.:

-   -   ProSe Application ID, indicates what the UE is interested to        announce.    -   UE Identity, IMSI (15 digits).    -   Announce command.    -   Application ID, represents a unique identifier of the UE        application that has triggered the transmission of the Discovery        Request message.    -   Discovery Entry ID, indicates whether this is a new request.    -   Requested Timer, optional, indicates the length of validity        timer associated with the ProSe Application Code.    -   Application-Level Container, optional, contains the request and        any relevant information for the ProSe Application Server to        assign a (set of) ProSe Application Code Suffix(es).    -   PC5_tech, optional, indicates the PC5 radio technology (e.g.        E-UTRA, WLAN) that UE wishes to use for announcements.

Referring to FIG. 7 , in some designs, the sidelink discovery responsemessage may include (assuming code rate 2/3, 64QAM, 25% REs for DMRS,discovery request and response messages occupy 5 and 2 RBsrespectively), e.g.:

-   -   ProSe Application Code, corresponds to the ProSe Application ID        that was contained in the Discovery Request (184 bits).    -   Validity timer, indicates for how long this ProSe Application        Code is going to be valid.    -   Discovery Entry ID, indicates whether this is a new request.    -   PC5_tech, optional, indicates the PC5 radio technology(ies) that        is/are authorized to be used for the assigned ProSe Application        Code.

Referring to FIG. 7 , beam training can be based on either BTRS (asshown in FIG. 7 ) or DMRS. In some designs, the sidelink discoverymessage may be transmitted with wider beams while BTRS is transmittedwith narrower beams, in which case there is a 1-to-N mapping betweensidelink discovery beams and BTRS beams, as shown in FIG. 8A.

FIG. 8A illustrates a comparative illustration 800 depicting therelative widths of beams in accordance with aspects of the disclosure.In FIG. 8A, a wider beam 802 may be used for transmission of thesidelink discovery message, and narrower beams 804 and 806 may be usedfor transmission of BTRS. In this case, there is a 1:2 correspondencebetween sidelink discovery beams and BTRS beams (i.e., a 1:Ncorrespondence where N=2). With reference to FIG. 7 , in some designs,the BTRS is made narrower so that UE 2 may select a narrower beam (beamrefinement). FIG. 8B illustrates frequency utilizations 850 of BTRS andDMRS in accordance with aspects of the disclosure. As shown in FIG. 8B,BTRS occupies wider bandwidth than DMRS (e.g., BTRS provides RSRP acrossa wider bandwidth than DMRS).

Sidelink communication may be implemented over higher bands (e.g., FR2,FR2x, FR4), which may complicate the discovery process. As noted above,UEs on sidelink need to discovery each other to setup a connection. Insome designs, UEs need to perform beam training during the discoveryprocedure, as described above with respect to FIG. 7 . In some designs,without beam training, it is difficult for UEs to communicate thesidelink discovery messages and sidelink discovery response messages. InFIG. 7 , beam training is performed before the sidelink discoverymessage is communicated. Hence, all candidate responder UEs that detectBTRS may transmit the BT response (e.g., because the candidate responderUEs do not yet know if they are interested in connecting to theinitiator UE). This creates high system overhead in scenarios wherecandidate responder UEs perform beam training and transmit BT responses,but ultimately receive the sidelink discovery message and decide not toconnect (e.g., no sidelink discovery response message is sent).

Aspects of the disclosure are directed to a discovery procedure wherebyan initiator UE transmits sidelink discovery message(s) and BTRS(s)before a BT response is received from candidate responder UEs. In thiscase, the candidate responder UEs have an opportunity to review thesidelink discovery message(s) before transmission of a BT response. Suchaspects may provide various technical advantages, such as reducingdiscovery overhead, reducing spectral interference, and so on.

FIG. 9 illustrates an exemplary process 900 of communications accordingto an aspect of the disclosure. The process 900 of FIG. 9 is performedby a UE, which may correspond to UE 302 as an example.

Referring to FIG. 9 , at 910, the initiator UE (e.g., transmitter 314 or324, etc.) transmits a sidelink BTRS a first number of times on each ofa first set of beams. Below, the first number of times (or BTRSrepetition number) is denoted as M and the number of beams in the firstset of beams is denoted as N (or N_(BTRS)). In some designs, thetransmission of the sidelink BTRSs may be implemented via a “beamsweeping” technique, as described above. In some designs, the sidelinkBTRSs are transmitted (e.g., via beam sweeping) in order betweensuccessively adjacent beams among the first set of beams. In otherdesigns, the sidelink BTRSs are transmitted via interleaving of thefirst set of beams (e.g., in other words, the sequence of beams overwhich the beam sweeping of the sidelink BTRSs is implemented may bedisordered, as described below in more detail).

Referring to FIG. 9 , at 920, the initiator UE (e.g., transmitter 314 or324, etc.) transmits a sidelink discovery message a second number oftimes on each of a second set of beams, wherein each beam from thesecond set of beams is associated with at least one beam from the firstset of beams. Below, the number of beams in the first set of beams isdenoted as N (or N_(disc)). The second number of times may be the sameor different than the first number of times (M). In some designs, eachbeam from the second set of beams may spatially overlap with some or allof one (or more) beam from the first set of beams (e.g., 1:1 or N:1mapping between the first set of beams and the second set of beams, withN being greater than 1), as described below in more detail). In somedesigns, the transmission of the sidelink discovery messages at 920follows the transmission of the sidelink BTRSs at 910. In other designs,the transmission of the sidelink BTRSs at 910 follows the transmissionof the sidelink discovery messages at 920. In some designs, thetransmission of the sidelink discovery messages may be implemented via a“beam sweeping” technique, as described above. In some designs, thesidelink discovery messages are transmitted (e.g., via beam sweeping) inorder between successively adjacent beams among the first set of beams.In other designs, the sidelink discovery messages are transmitted viainterleaving of the first set of beams (e.g., in other words, thesequence of beams over which the beam sweeping of the sidelink discoverymessages is implemented may be disordered, as described below in moredetail).

Referring to FIG. 9 , at 930, the initiator UE (e.g., receiver 312 or322, etc.) receives, from at least one responder UE after thetransmission of the sidelink BTRSs and the sidelink discovery messages,a BT response signal and a sidelink discovery response message on a beamcorresponding to (e.g., having beam reciprocity with respect to) one ofthe first set of beams. In some designs, the BT response signal mayinclude a preamble (e.g., similar to CSI-RS and separate fromPSCCH/PSSCH). In other designs, the BT response signal may include amessage (e.g., a sidelink discovery response message). For example, themessage may be received as part of PSCCH/PSSCH.

FIG. 10 illustrates an exemplary process 1000 of communicationsaccording to an aspect of the disclosure. The process 1000 of FIG. 10 isperformed by a UE, which may correspond to UE 302 as an example.

Referring to FIG. 10 , at 1010, the responder UE (e.g., receiver 312 or322, etc.) receives, from an initiator UE, a sidelink BTRS a firstnumber of times on each of a first set of beams. Below, the first numberof times (or BTRS repetition number) is denoted as M and the number ofbeams in the first set of beams is denoted as N (or N_(BTRS)). In somedesigns, the reception of the sidelink BTRSs may be implemented via a“beam sweeping” technique, as described above. In some designs, thesidelink BTRSs are received (e.g., via beam sweeping) in order betweensuccessively adjacent beams among the first set of beams. In otherdesigns, the sidelink BTRSs are received via interleaving of the firstset of beams (e.g., in other words, the sequence of beams over which thebeam sweeping of the sidelink BTRSs is implemented may be disordered, asdescribed below in more detail).

Referring to FIG. 10 , at 1020, the responder UE (e.g., receiver 312 or322, etc.) receives, from the initiator UE, a sidelink discovery messagea second number of times on each of a second set of beams, wherein eachbeam from the second set of beams is associated with at least one beamfrom the first set of beams. Below, the number of beams in the first setof beams is denoted as N (or N_(disc)). The second number of times (orsidelink discovery message repetition number) may be the same ordifferent than the first number of times. In some designs, each beamfrom the second set of beams may spatially overlap with some or all ofone (or more) beam from the first set of beams (e.g., 1:1 or N:1 mappingbetween the first set of beams and the second set of beams, with N beinggreater than 1), as described below in more detail). In some designs,the reception of the sidelink discovery messages at 1020 follows thereception of the sidelink BTRSs at 1010. In other designs, the receptionof the sidelink BTRSs at 1010 follows the reception of the sidelinkdiscovery messages at 1020. In some designs, the reception of thesidelink discovery messages may be implemented via a “beam sweeping”technique, as described above. In some designs, the sidelink discoverymessages are received (e.g., via beam sweeping) in order betweensuccessively adjacent beams among the first set of beams. In otherdesigns, the sidelink discovery messages are transmitted viainterleaving of the first set of beams (e.g., in other words, thesequence of beams over which the beam sweeping of the sidelink discoverymessages is implemented may be disordered, as described below in moredetail).

Referring to FIG. 10 , at 1030, the responder UE (e.g., transmitter 314or 324, etc.) transmits, to the initiator UE, a BT response signal and asidelink discovery response message on a beam that corresponds to (e.g.,has beam reciprocity with respect to) one of the first set of beams. Insome designs, the BT response signal may include a preamble (e.g.,similar to CSI-RS and separate from PSCCH/PSSCH). In other designs, theBT response signal may include a message (e.g., a sidelink discoveryresponse message). For example, the message may be received as part ofPSCCH/PSSCH.

Referring to FIGS. 9-10 , in some designs as noted above, each beamamong the first set of beams is associated with a first width, and eachbeam among the second set of beams is associated with a second widththat is wider than the first width. One example of such animplementation is described above with respect to FIG. 8A, where a widerbeam 802 may be used for transmission of the sidelink discovery message,and narrower beams 804 and 806 may be used for transmission of BTRS. Inthis case, there is a N:1 mapping between the first set of beams and thesecond set of beams, with N being greater than 1. In some designs, twoor more beams among the first set of beams correspond to a single beamamong the second set of beams (e.g., N>=2). In other designs, each beamamong the first set of beams is associated with the same width as eachbeam among the second set of beams. In this case, there is a 1:1 mappingbetween the first set of beams and the second set of beams.

FIG. 11 illustrates a discovery procedure 1100 based on an exampleimplementation of the processes 900-1000 of FIGS. 9-10 in accordancewith aspects of the disclosure. FIG. 12 illustrates a signaling sequence1200 associated with the discovery procedure 1100 of FIG. 11 .

Referring to FIGS. 11-12 , similar to FIG. 7 , at 1202, UE 1 transmitsBTRS upon N transmit beams (N=3) with M repetitions (M=2) per beamacross 6 total slots (M×N=2×3=6). In some designs, M=2 may be based onan expectation that the candidate responder UEs (e.g., UE 2) aremonitoring for sidelink discovery messages on two receive beams (e.g.,alternating between the respective receive beams). In other words,repeating BTRS M times will ensure that a responder UE with M receivebeams will have a chance to detect BTRS on each of its receive beams. UE2 receives the beam sweeping of BTRS on some or all of the N beams andselects the beam among UE 2's M beams with correspondence to the bestBTRS beam (i.e., the selected beam is now paired with the best BTRSbeam).

Referring to FIGS. 11-12 , unlike FIG. 7 , UE 2 does not automaticallyrespond to the BTRS with a BT response signal. Instead, at 1204, UE 1further transmits the sidelink discovery message on the N transmit beams(e.g., in this case, with a single repetition per beam as shown in FIG.11 ). Because UE 2 receives the sidelink discovery message before a BTresponse signal is sent by UE 2, UE 2 can analyze the sidelink discoverymessage and determine whether or not to respond to the sidelinkdiscovery message (e.g., so in some cases, some responder UEs may decodethe sidelink discovery message and then opt not to respond with a BTresponse signal or sidelink discovery response message). At 1206, assumethat UE 2 decides to respond to the sidelink discovery message from1204, and thereby transmits a BT response signal 1206 and a sidelinkdiscovery response message at 1208. Hence, at least some candidateresponder UEs may read the sidelink discovery message and opt not torespond with a BT response signal, which reduces interference andoverhead in the system.

FIG. 13 illustrates a discovery procedure 1300 based on an exampleimplementation of the processes 900-1000 of FIGS. 9-10 in accordancewith aspects of the disclosure. Similar to FIG. 11 , the discoveryprocedure 1300 may also be associated with the signaling sequence 1200of FIG. 12 . In FIG. 13 , the sidelink discovery message is transmittedvia wider beams 802 as depicted in FIG. 8A, and the BTRS is transmittedvia narrower beams 804-806 as depicted in FIG. 8A. In particular, thereis an N:1 mapping between BTRS beams and sidelink discovery beams, whereN=2 or 2:1 mapping. In some designs, using narrower beam widths for BTRSmay help to reduce or avoid further beam refinement after a connectionis established between the initiator UE and the responder UE. Hence,N_(disc)=3 and N_(BTRS)=6. In FIG. 13 , the BTRS and discovery messagestransmitted via “ordered” beam sweeping. In other words, the sidelinkBTRSs are transmitted in order between successively adjacent beams amongthe first set of beams, and the sidelink discovery messages are alsotransmitted in order between successively adjacent beams among thesecond set of beams. The discovery procedure 1300 of FIG. 13 isotherwise the same as the discovery procedure 1100 of FIG. 11 , and assuch will not be discussed further for the sake of brevity.

FIG. 14 illustrates a discovery procedure 1400 based on an exampleimplementation of the processes 900-1000 of FIGS. 9-10 in accordancewith aspects of the disclosure. Similar to FIG. 11 , the discoveryprocedure 1400 may also be associated with the signaling sequence 1200of FIG. 12 . In FIG. 14 , the sidelink discovery message is transmittedvia wider beams 802 as depicted in FIG. 8A, and the BTRS is transmittedvia narrower beams 804-806 as depicted in FIG. 8A. In particular, thereis an N:1 mapping between BTRS beams and sidelink discovery beams, whereN=2 or 2:1 mapping. Hence, N_(disc)=3 and N_(BTRS)=6. Unlike FIG. 13where the BTRS and discovery messages transmitted via “ordered” beamsweeping, in FIG. 14 the BTRS and discovery messages are transmitted viainterleaved (or “unordered”) beam sweeping. More specifically, insteadof transmitting BTRS beams {0, 1, . . . , N_(BTRS)−1} in order, the BTRSbeams are disordered before transmission, e.g., {3, 0, N_(BTRS)−1, . . ., 6}. In some designs, interleaving order of the BTRS beams and the BTresponse is preconfigured, which is known to all UEs. In some designs,interleaved or unordered beam sweeping may reduce or avoid an influenceof temporary blocking on measurement (e.g., sometimes, a temporary blockmay reduce measurement quality on an otherwise good beam pair). Thediscovery procedure 1400 of FIG. 14 is otherwise the same as thediscovery procedure 1300 of FIG. 13 , and as such will not be discussedfurther for the sake of brevity.

Referring to FIGS. 9-14 , assuming that N_(BTRS)=N_(disc), the overheadis N×M×BTRS+N×DISC+N×V×BT_Resp+V×DISC_Resp, where N is the number of Txbeams, M is the number of Rx beams, V is the number of responder UEs,and BTRS, BT_Resp, DISC and DISC_Resp are the overhead of beam trainingreference signal, beam training response preamble, discovery message anddiscovery response message, respectively. Under these assumptions, insome designs:

-   -   Assuming V≤N, and there is no collision between UEs.    -   N×M×BTRS because UE 1 repeats BTRS N_BTRS×M times.    -   N×DISC because UE 2 knows the optimal Rx beam, so UE 1 only        repeats discovery message N_disc times.    -   N×V×BT_Resp because only the target UEs need to respond to UE 1,        and UE 1 receives the response from all directions.    -   V×DISC_Resp because the beam pair between UE 1 and UE 2 has been        established, the discovery response does not require beam        sweeping.    -   If V>N, or collision between BT response, UE 1 may repeat BTRS        and sidelink discovery transmission multiple times to receive        more responses.

While FIGS. 11-14 relate to scenarios where transmission of the sidelinkdiscovery message follows transmission of the BTRS, in other designs,transmission BTRS of the follows transmission of the sidelink discoverymessage. Such aspects are described below with respect to FIGS. 15-18 .Generally, for scenarios where the sidelink discovery message followstransmission of the BTRS as in FIGS. 11-14 , the sidelink discoverymessage can be transmitted using the beam pair established via BTRS(e.g., good for delivery of sidelink discovery message). For scenarioswhere the sidelink discovery message precedes transmission of the BTRSas in FIGS. 15-18 , UEs that choose not to respond to the originating UEmay skip the BTRS (e.g., good for power saving).

FIG. 15 illustrates a discovery procedure 1500 based on an exampleimplementation of the processes 900-1000 of FIGS. 9-10 in accordancewith aspects of the disclosure. FIG. 16 illustrates a signaling sequence1600 associated with the discovery procedure 1500 of FIG. 15 .

Referring to FIGS. 15-16 , at 1602, UE 1 transmits the sidelinkdiscovery message on the N (N=3) transmit beams (e.g., in this case,with two repetitions per beam as shown in FIG. 15 ). At 1604, UE 1transmits BTRS upon N transmit beams (N=3) with M repetitions (M=2) perbeam across 6 total slots (M×N=2×3=6). In some designs, M=2 may be basedon an expectation that the candidate responder UEs (e.g., UE 2) aremonitoring for sidelink discovery messages on two receive beams (e.g.,alternating between the respective receive beams). In other words,repeating BTRS M times will ensure that a responder UE with M receivebeams will have a chance to detect BTRS on each of its receive beams. UE2 receives the beam sweeping of BTRS on some or all of the N beams andselects the beam among UE 2's M beams with correspondence to the bestBTRS beam (i.e., the selected beam is now paired with the best BTRSbeam).

Referring to FIGS. 15-16 , unlike FIG. 7 , UE 2 does not automaticallyrespond to the BTRS with a BT response signal. Instead, because UE 2receives the sidelink discovery message before a BT response signal issent by UE 2, UE 2 can analyze the sidelink discovery message anddetermine whether or not to respond to the sidelink discovery message(e.g., so in some cases, some responder UEs may decode the sidelinkdiscovery message and then opt not to respond with a BT response signalor sidelink discovery response message). At 1606, assume that UE 2decides to respond to the sidelink discovery message from 1602, andthereby transmits a BT response signal 1606 and a sidelink discoveryresponse message at 1608. Hence, at least some candidate responder UEsmay read the sidelink discovery message and opt not to respond with a BTresponse signal, which reduces interference and overhead in the system.

FIG. 17 illustrates a discovery procedure 1700 based on an exampleimplementation of the processes 900-1000 of FIGS. 9-10 in accordancewith aspects of the disclosure. Similar to FIG. 15 , the discoveryprocedure 1700 may also be associated with the signaling sequence 1600of FIG. 16 . In FIG. 17 , the sidelink discovery message is transmittedvia wider beams 802 as depicted in FIG. 8A, and the BTRS is transmittedvia narrower beams 804-806 as depicted in FIG. 8A. In particular, thereis an N:1 mapping between BTRS beams and sidelink discovery beams, whereN=2 or 2:1 mapping. In some designs, using narrower beam widths for BTRSmay help to reduce or avoid further beam refinement after a connectionis established between the initiator UE and the responder UE. Hence,N_(disc)=3 and N_(BTRS)=6. In FIG. 17 , the BTRS and discovery messagestransmitted via “ordered” beam sweeping. In other words, the sidelinkBTRSs are transmitted in order between successively adjacent beams amongthe first set of beams, and the sidelink discovery messages are alsotransmitted in order between successively adjacent beams among thesecond set of beams. The discovery procedure 1700 of FIG. 17 isotherwise the same as the discovery procedure 1500 of FIG. 15 , and assuch will not be discussed further for the sake of brevity.

FIG. 18 illustrates a discovery procedure 1800 based on an exampleimplementation of the processes 900-1000 of FIGS. 9-10 in accordancewith aspects of the disclosure. Similar to FIG. 15 , the discoveryprocedure 1800 may also be associated with the signaling sequence 1600of FIG. 16 . In FIG. 18 , the sidelink discovery message is transmittedvia wider beams 802 as depicted in FIG. 8A, and the BTRS is transmittedvia narrower beams 804-806 as depicted in FIG. 8A. In particular, thereis an N:1 mapping between BTRS beams and sidelink discovery beams, whereN=2 or 2:1 mapping. Hence, N_(disc)=3 and N_(BTRS)=6. Unlike FIG. 17where the BTRS and discovery messages transmitted via “ordered” beamsweeping, in FIG. 18 the BTRS and discovery messages are transmitted viainterleaved (or “unordered”) beam sweeping. More specifically, insteadof transmitting BTRS beams {0, 1, . . . , N_(BTRS)−1} in order, the BTRSbeams are disordered before transmission, e.g., {3, 0, N_(BTRS)−1, . . ., 6}. In some designs, interleaving order of the BTRS beams and the BTresponse is preconfigured, which is known to all UEs. In some designs,interleaved or unordered beam sweeping may reduce or avoid an influenceof temporary blocking on measurement (e.g., sometimes, a temporary blockmay reduce measurement quality on an otherwise good beam pair). Thediscovery procedure 1800 of FIG. 18 is otherwise the same as thediscovery procedure 1700 of FIG. 17 , and as such will not be discussedfurther for the sake of brevity.

Referring to FIGS. 15-18 , assuming that N_(BTRS)=N_(disc), the totalRBs occupied is N×M×(BTRS+DISC)+N×V×BT_Resp+V×DISC_Resp, where N is thenumber of Tx beams, M is the number of Rx beams, V is the number ofresponder UEs, and BTRS, BT_Resp, DISC and DISC_Resp are the RBs of beamtraining reference signal, beam training response preamble, discoverymessage and discovery response message, respectively. Under theseassumptions, in some designs:

-   -   N×M×(BTRS+DISC) because UE 1 repeats BTRS and discovery message        N×M times    -   N×V×BT_Resp because only the target UEs need to respond to UE 1,        and UE 1 receives the response from all directions    -   V×DISC_Resp because the beam pair between UE 1 and UE 2 has been        established, the discovery response does not require beam        sweeping

In some designs, the discovery procedure 700 of FIG. 7 is generallyassociated with higher overhead as compared to any of the disclosureprocedures described with respect to FIGS. 9-18 . However, the discoveryprocedure 700 of FIG. 7 is also in more reliable, because a beam pair isestablished before the sidelink discovery message is transmitted. Insome designs, the discovery procedures described between FIGS. 15-18 maygrant some responder UEs an opportunity to skip beam training (i.e.,BTRS reception altogether). For example, if UE 2 is capable of decodingthe sidelink discovery message in FIGS. 15-18 and determines that it isnot interested in responding, then performing the subsequent beamtraining via BTRS can be skipped (e.g., in contrast to FIGS. 11-14 ,where the BTRS is transmitted first).

FIG. 19 is a conceptual data flow diagram 1900 illustrating the dataflow between different means/components in exemplary apparatuses 1902and 1980 in accordance with an aspect of the disclosure. The apparatus1902 may be an initiator UE (e.g., UE 302) in communication with anapparatus 1980, which may be a responder UE (e.g., UE 302).

The apparatus 1902 includes a transmission component 1904, which maycorrespond to transmitter circuitry in UE 302 as depicted in FIG. 3A,including transmitter(s) 314 and 324, antenna(s) 316 and 326, etc. Theapparatus 1902 further includes Discovery component 1906, which maycorrespond to processor circuitry in UE 302 as depicted in FIG. 3A,including processing system 332, etc. The apparatus 1902 furtherincludes a reception component 1908, which may correspond to receivercircuitry in UE 302 as depicted in FIG. 3A, including receiver(s) 312and 322, antenna(s) 316 and 326, etc.

The apparatus 1980 includes a transmission component 1986, which maycorrespond to transmitter circuitry in UE 302 as depicted in FIG. 3A,including transmitter(s) 314 and 324, antenna(s) 316 and 326, etc. Theapparatus 1980 further includes Discovery component 1984, which maycorrespond to processor circuitry in UE 302 as depicted in FIG. 3A,including processing system 332, etc. The apparatus 1980 furtherincludes a reception component 1982, which may correspond to receivercircuitry in UE 302 as depicted in FIG. 3A, including receiver(s) 312and 322, antenna(s) 316 and 326, etc.

Referring to FIG. 19 , the discovery component 1906 directs thetransmission component 1904 transmits sidelink discovery message andBTRS on multiple beams and repetition(s) (in either order, as describedabove). The reception component 1982 receives the sidelink discoverymessage and BTRS, and the discovery component 1984 decides to respond tothe sidelink discovery message. The discovery component 1984 directs thetransmission component 1986 to transmit a BT response and a sidelinkdiscovery response message to the reception component 1908.

One or more components of the apparatus 1902 and apparatus 1980 mayperform each of the blocks of the algorithm in the aforementionedflowcharts of FIGS. 9-10 . As such, each block in the aforementionedflowcharts of FIGS. 9-10 may be performed by a component and theapparatus 1902 and apparatus 1980 may include one or more of thosecomponents. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 20 is a diagram 2000 illustrating an example of a hardwareimplementation for an apparatus 1902 employing a processing system 2014.The processing system 2014 may be implemented with a bus architecture,represented generally by the bus 2024. The bus 2024 may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system 2014 and the overall designconstraints. The bus 2024 links together various circuits including oneor more processors and/or hardware components, represented by theprocessor 2004, the components 1904, 1906 and 1908, and thecomputer-readable medium/memory 2006. The bus 2024 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 2014 may be coupled to a transceiver 2010. Thetransceiver 2010 is coupled to one or more antennas 2020. Thetransceiver 2010 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 2010 receives asignal from the one or more antennas 2020, extracts information from thereceived signal, and provides the extracted information to theprocessing system 2014, specifically the reception component 1908. Inaddition, the transceiver 2010 receives information from the processingsystem 2014, specifically the transmission component 1904, and based onthe received information, generates a signal to be applied to the one ormore antennas 2020. The processing system 2014 includes a processor 2004coupled to a computer-readable medium/memory 2006. The processor 2004 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 2006. The software, whenexecuted by the processor 2004, causes the processing system 2014 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 2006 may also be used forstoring data that is manipulated by the processor 2004 when executingsoftware. The processing system 2014 further includes at least one ofthe components 1904, 1906 and 1908. The components may be softwarecomponents running in the processor 2004, resident/stored in thecomputer readable medium/memory 2006, one or more hardware componentscoupled to the processor 2004, or some combination thereof.

In one configuration, the apparatus 1902 (e.g., a UE) for wirelesscommunication includes means for transmitting a sidelink beam training(BT) reference signal (BTRS) a first number of times on each of a firstset of beams, means for transmitting a sidelink discovery message asecond number of times on each of a second set of beams, wherein eachbeam from the second set of beams is associated with at least one beamfrom the first set of beams, and receiving, from at least one responderUE after the transmission of the sidelink BTRSs and the sidelinkdiscovery messages, a BT response signal and a sidelink discoveryresponse message on a beam corresponding to one of the first set ofbeams.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1902 and/or the processing system 2014 ofthe apparatus 1902 configured to perform the functions recited by theaforementioned means.

FIG. 21 is a diagram 2100 illustrating an example of a hardwareimplementation for an apparatus 1980 employing a processing system 2114.The processing system 2114 may be implemented with a bus architecture,represented generally by the bus 2124. The bus 2124 may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system 2114 and the overall designconstraints. The bus 2124 links together various circuits including oneor more processors and/or hardware components, represented by theprocessor 2104, the components 1982, 1984 and 1986, and thecomputer-readable medium/memory 2106. The bus 2124 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 2114 may be coupled to a transceiver 2110. Thetransceiver 2110 is coupled to one or more antennas 2120. Thetransceiver 2110 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 2110 receives asignal from the one or more antennas 2120, extracts information from thereceived signal, and provides the extracted information to theprocessing system 2114, specifically the reception component 1982. Inaddition, the transceiver 2110 receives information from the processingsystem 2114, specifically the transmission component 1986, and based onthe received information, generates a signal to be applied to the one ormore antennas 2120. The processing system 2114 includes a processor 2104coupled to a computer-readable medium/memory 2106. The processor 2104 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 2106. The software, whenexecuted by the processor 2104, causes the processing system 2114 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 2106 may also be used forstoring data that is manipulated by the processor 2104 when executingsoftware. The processing system 2114 further includes at least one ofthe components 1982, 1984 and 1986. The components may be softwarecomponents running in the processor 2104, resident/stored in thecomputer readable medium/memory 2106, one or more hardware componentscoupled to the processor 2104, or some combination thereof.

In one configuration, the apparatus 1980 (e.g., a UE) for wirelesscommunication may include means for receiving, from an initiator UE, asidelink beam training (BT) reference signal (BTRS) a first number oftimes on each of a first set of beams, means for receiving, from theinitiator UE, a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams,and means for transmitting, to the initiator UE, a BT response signaland a sidelink discovery response message on a beam that corresponds toone of the first set of beams.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1980 and/or the processing system 2114 ofthe apparatus 1980 configured to perform the functions recited by theaforementioned means.

In the detailed description above it can be seen that different featuresare grouped together in examples. This manner of disclosure should notbe understood as an intention that the example clauses have morefeatures than are explicitly mentioned in each clause. Rather, thevarious aspects of the disclosure may include fewer than all features ofan individual example clause disclosed. Therefore, the following clausesshould hereby be deemed to be incorporated in the description, whereineach clause by itself can stand as a separate example. Although eachdependent clause can refer in the clauses to a specific combination withone of the other clauses, the aspect(s) of that dependent clause are notlimited to the specific combination. It will be appreciated that otherexample clauses can also include a combination of the dependent clauseaspect(s) with the subject matter of any other dependent clause orindependent clause or a combination of any feature with other dependentand independent clauses. The various aspects disclosed herein expresslyinclude these combinations, unless it is explicitly expressed or can bereadily inferred that a specific combination is not intended (e.g.,contradictory aspects, such as defining an element as both an insulatorand a conductor). Furthermore, it is also intended that aspects of aclause can be included in any other independent clause, even if theclause is not directly dependent on the independent clause.

Implementation examples are described in the following numbered clauses:

Clause 1. A method of operating an initiator user equipment (UE),comprising: transmitting a sidelink beam training (BT) reference signal(BTRS) a first number of times on each of a first set of beams;transmitting a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and receiving, from at least one responder UE after the transmission ofthe sidelink BTRSs and the sidelink discovery messages, a BT responsesignal and a sidelink discovery response message on a beam correspondingto one of the first set of beams.

Clause 2. The method of clause 1, wherein the transmission of thesidelink discovery messages follows the transmission of the sidelinkBTRSs.

Clause 3. The method of any of clauses 1 to 2, wherein the transmissionof the sidelink BTRSs follows the transmission of the sidelink discoverymessages.

Clause 4. The method of any of clauses 1 to 3, wherein the first numberof times is the same as the second number of times.

Clause 5. The method of any of clauses 1 to 4, wherein the first numberof times is greater than the second number of times.

Clause 6. The method of any of clauses 1 to 5, wherein each beam amongthe first set of beams is associated with the same width as each beamamong the second set of beams.

Clause 7. The method of clause 6, wherein there is a 1:1 mapping betweenthe first set of beams and the second set of beams.

Clause 8. The method of any of clauses 1 to 7, wherein each beam amongthe first set of beams is associated with a first width, and whereineach beam among the second set of beams is associated with a secondwidth that is wider than the first width.

Clause 9. The method of clause 8, wherein there is a N:1 mapping betweenthe first set of beams and the second set of beams, with N being greaterthan 1.

Clause 10. The method of any of clauses 1 to 9, wherein two or morebeams among the first set of beams correspond to a single beam among thesecond set of beams.

Clause 11. The method of any of clauses 1 to 10, wherein the sidelinkBTRSs are transmitted in order between successively adjacent beams amongthe first set of beams, or wherein the sidelink discovery messages aretransmitted in order between successively adjacent beams among thesecond set of beams, or a combination thereof.

Clause 12. The method of any of clauses 1 to 11, wherein the sidelinkBTRSs are transmitted via interleaving of the first set of beams, orwherein the sidelink discovery messages are transmitted via interleavingof the second set of beams, or a combination thereof.

Clause 13. The method of any of clauses 1 to 12, wherein the BT responsesignal comprises a preamble or a message.

Clause 14. A method of operating responder user equipment (UE),comprising: receiving, from an initiator UE, a sidelink beam training(BT) reference signal (BTRS) a first number of times on each of a firstset of beams; receiving, from the initiator UE, a sidelink discoverymessage a second number of times on each of a second set of beams,wherein each beam from the second set of beams is associated with atleast one beam from the first set of beams; and transmitting, to theinitiator UE, a BT response signal and a sidelink discovery responsemessage on a beam that corresponds to one of the first set of beams.

Clause 15. The method of clause 14, wherein the reception of thesidelink discovery messages follows the reception of the sidelink BTRSs.

Clause 16. The method of any of clauses 14 to 15, wherein the receptionof the sidelink BTRSs follows the reception of the sidelink discoverymessages.

Clause 17. The method of any of clauses 14 to 16, wherein the firstnumber of times is the same as the second number of times.

Clause 18. The method of any of clauses 14 to 17, wherein the firstnumber of times is greater than the second number of times.

Clause 19. The method of any of clauses 14 to 18, wherein each beamamong the first set of beams is associated with the same width as eachbeam among the second set of beams.

Clause 20. The method of clause 19, wherein there is a 1:1 mappingbetween the first set of beams and the second set of beams.

Clause 21. The method of any of clauses 14 to 20, wherein each beamamong the first set of beams is associated with a first width, andwherein each beam among the second set of beams is associated with asecond width that is wider than the first width.

Clause 22. The method of clause 21, wherein there is a N:1 mappingbetween the first set of beams and the second set of beams, with N beinggreater than 1.

Clause 23. The method of any of clauses 14 to 22, wherein two or morebeams among the first set of beams correspond to a single beam among thesecond set of beams.

Clause 24. The method of any of clauses 14 to 23, wherein the sidelinkBTRSs are received in order between successively adjacent beams amongthe first set of beams, or wherein the sidelink discovery messages arereceived in order between successively adjacent beams among the secondset of beams, or a combination thereof.

Clause 25. The method of any of clauses 14 to 24, wherein the sidelinkBTRS s are received via interleaving of the first set of beams, orwherein the sidelink discovery messages are received via interleaving ofthe second set of beams, or a combination thereof.

Clause 26. The method of any of clauses 14 to 25, wherein the BTresponse signal comprises a preamble or a message.

Clause 27. An initiator user equipment (UE), comprising: a memory; atleast one transceiver; and at least one processor communicativelycoupled to the memory and the at least one transceiver, the at least oneprocessor configured to: transmit, via the at least one transceiver, asidelink beam training (BT) reference signal (BTRS) a first number oftimes on each of a first set of beams; transmit, via the at least onetransceiver, a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and receive, via the at least one transceiver, from at least oneresponder UE after the transmission of the sidelink BTRSs and thesidelink discovery messages, a BT response signal and a sidelinkdiscovery response message on a beam corresponding to one of the firstset of beams.

Clause 28. The initiator UE of clause 27, wherein the transmission ofthe sidelink discovery messages follows the transmission of the sidelinkBTRSs.

Clause 29. The initiator UE of any of clauses 27 to 28, wherein thetransmission of the sidelink BTRSs follows the transmission of thesidelink discovery messages.

Clause 30. The initiator UE of any of clauses 27 to 29, wherein thefirst number of times is the same as the second number of times.

Clause 31. The initiator UE of any of clauses 27 to 30, wherein thefirst number of times is greater than the second number of times.

Clause 32. The initiator UE of any of clauses 27 to 31, wherein eachbeam among the first set of beams is associated with the same width aseach beam among the second set of beams.

Clause 33. The initiator UE of clause 32, wherein there is a 1:1 mappingbetween the first set of beams and the second set of beams.

Clause 34. The initiator UE of any of clauses 27 to 33, wherein eachbeam among the first set of beams is associated with a first width, andwherein each beam among the second set of beams is associated with asecond width that is wider than the first width.

Clause 35. The initiator UE of clause 34, wherein there is a N:1 mappingbetween the first set of beams and the second set of beams, with N beinggreater than 1.

Clause 36. The initiator UE of any of clauses 27 to 35, wherein two ormore beams among the first set of beams correspond to a single beamamong the second set of beams.

Clause 37. The initiator UE of any of clauses 27 to 36, wherein thesidelink BTRSs are transmitted in order between successively adjacentbeams among the first set of beams, or wherein the sidelink discoverymessages are transmitted in order between successively adjacent beamsamong the second set of beams, or a combination thereof.

Clause 38. The initiator UE of any of clauses 27 to 37, wherein thesidelink BTRSs are transmitted via interleaving of the first set ofbeams, or wherein the sidelink discovery messages are transmitted viainterleaving of the second set of beams, or a combination thereof.

Clause 39. The initiator UE of any of clauses 27 to 38, wherein the BTresponse signal comprises a preamble or a message.

Clause 40. A responder user equipment (UE), comprising: a memory; atleast one transceiver; and at least one processor communicativelycoupled to the memory and the at least one transceiver, the at least oneprocessor configured to: receive, via the at least one transceiver, froman initiator UE, a sidelink beam training (BT) reference signal (BTRS) afirst number of times on each of a first set of beams; receive, via theat least one transceiver, from the initiator UE, a sidelink discoverymessage a second number of times on each of a second set of beams,wherein each beam from the second set of beams is associated with atleast one beam from the first set of beams; and transmit, via the atleast one transceiver, to the initiator UE, a BT response signal and asidelink discovery response message on a beam that corresponds to one ofthe first set of beams.

Clause 41. The responder UE of clause 40, wherein the reception of thesidelink discovery messages follows the reception of the sidelink BTRSs.

Clause 42. The responder UE of any of clauses 40 to 41, wherein thereception of the sidelink BTRSs follows the reception of the sidelinkdiscovery messages.

Clause 43. The responder UE of any of clauses 40 to 42, wherein thefirst number of times is the same as the second number of times.

Clause 44. The UE of any of clauses 40 to 43, wherein the first numberof times is greater than the second number of times.

Clause 45. The responder UE of any of clauses 40 to 44, wherein eachbeam among the first set of beams is associated with the same width aseach beam among the second set of beams.

Clause 46. The responder UE of clause 45, wherein there is a 1:1 mappingbetween the first set of beams and the second set of beams.

Clause 47. The responder UE of any of clauses 40 to 46, wherein eachbeam among the first set of beams is associated with a first width, andwherein each beam among the second set of beams is associated with asecond width that is wider than the first width.

Clause 48. The responder UE of clause 47, wherein there is a N:1 mappingbetween the first set of beams and the second set of beams, with N beinggreater than 1.

Clause 49. The responder UE of any of clauses 40 to 48, wherein two ormore beams among the first set of beams correspond to a single beamamong the second set of beams.

Clause 50. The responder UE of any of clauses 40 to 49, wherein thesidelink BTRSs are received in order between successively adjacent beamsamong the first set of beams, or wherein the sidelink discovery messagesare received in order between successively adjacent beams among thesecond set of beams, or a combination thereof.

Clause 51. The responder UE of any of clauses 40 to 50, wherein thesidelink BTRSs are received via interleaving of the first set of beams,or wherein the sidelink discovery messages are received via interleavingof the second set of beams, or a combination thereof.

Clause 52. The responder UE of any of clauses 40 to 51, wherein the BTresponse signal comprises a preamble or a message.

Clause 53. An initiator user equipment (UE), comprising: means fortransmitting a sidelink beam training (BT) reference signal (BTRS) afirst number of times on each of a first set of beams; means fortransmitting a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and means for receiving, from at least one responder UE after thetransmission of the sidelink BTRSs and the sidelink discovery messages,a BT response signal and a sidelink discovery response message on a beamcorresponding to one of the first set of beams.

Clause 54. The initiator UE of clause 53, wherein the transmission ofthe sidelink discovery messages follows the transmission of the sidelinkBTRSs.

Clause 55. The initiator UE of any of clauses 53 to 54, wherein thetransmission of the sidelink BTRSs follows the transmission of thesidelink discovery messages.

Clause 56. The initiator UE of any of clauses 53 to 55, wherein thefirst number of times is the same as the second number of times.

Clause 57. The initiator UE of any of clauses 53 to 56, wherein thefirst number of times is greater than the second number of times.

Clause 58. The initiator UE of any of clauses 53 to 57, wherein eachbeam among the first set of beams is associated with the same width aseach beam among the second set of beams.

Clause 59. The initiator UE of clause 58, wherein there is a 1:1 mappingbetween the first set of beams and the second set of beams.

Clause 60. The initiator UE of any of clauses 53 to 59, wherein eachbeam among the first set of beams is associated with a first width, andwherein each beam among the second set of beams is associated with asecond width that is wider than the first width.

Clause 61. The initiator UE of clause 60, wherein there is a N:1 mappingbetween the first set of beams and the second set of beams, with N beinggreater than 1.

Clause 62. The initiator UE of any of clauses 53 to 61, wherein two ormore beams among the first set of beams correspond to a single beamamong the second set of beams.

Clause 63. The initiator UE of any of clauses 53 to 62, wherein thesidelink BTRSs are transmitted in order between successively adjacentbeams among the first set of beams, or wherein the sidelink discoverymessages are transmitted in order between successively adjacent beamsamong the second set of beams, or a combination thereof.

Clause 64. The initiator UE of any of clauses 53 to 63, wherein thesidelink BTRSs are transmitted via interleaving of the first set ofbeams, or wherein the sidelink discovery messages are transmitted viainterleaving of the second set of beams, or a combination thereof.

Clause 65. The initiator UE of any of clauses 53 to 64, wherein the BTresponse signal comprises a preamble or a message.

Clause 66. A responder user equipment (UE), comprising: means forreceiving, from an initiator UE, a sidelink beam training (BT) referencesignal (BTRS) a first number of times on each of a first set of beams;means for receiving, from the initiator UE, a sidelink discovery messagea second number of times on each of a second set of beams, wherein eachbeam from the second set of beams is associated with at least one beamfrom the first set of beams; and means for transmitting, to theinitiator UE, a BT response signal and a sidelink discovery responsemessage on a beam that corresponds to one of the first set of beams.

Clause 67. The responder UE of clause 66, wherein the reception of thesidelink discovery messages follows the reception of the sidelink BTRSs.

Clause 68. The responder UE of any of clauses 66 to 67, wherein thereception of the sidelink BTRSs follows the reception of the sidelinkdiscovery messages.

Clause 69. The responder UE of any of clauses 66 to 68, wherein thefirst number of times is the same as the second number of times.

Clause 70. The responder UE of any of clauses 66 to 69, wherein thefirst number of times is greater than the second number of times.

Clause 71. The responder UE of any of clauses 66 to 70, wherein eachbeam among the first set of beams is associated with the same width aseach beam among the second set of beams.

Clause 72. The responder UE of clause 71, wherein there is a 1:1 mappingbetween the first set of beams and the second set of beams.

Clause 73. The responder UE of any of clauses 66 to 72, wherein eachbeam among the first set of beams is associated with a first width, andwherein each beam among the second set of beams is associated with asecond width that is wider than the first width.

Clause 74. The responder UE of clause 73, wherein there is a N:1 mappingbetween the first set of beams and the second set of beams, with N beinggreater than 1.

Clause 75. The responder UE of any of clauses 66 to 74, wherein two ormore beams among the first set of beams correspond to a single beamamong the second set of beams.

Clause 76. The responder UE of any of clauses 66 to 75, wherein thesidelink BTRSs are received in order between successively adjacent beamsamong the first set of beams, or wherein the sidelink discovery messagesare received in order between successively adjacent beams among thesecond set of beams, or a combination thereof.

Clause 77. The responder UE of any of clauses 66 to 76, wherein thesidelink BTRSs are received via interleaving of the first set of beams,or wherein the sidelink discovery messages are received via interleavingof the second set of beams, or a combination thereof.

Clause 78. The responder UE of any of clauses 66 to 77, wherein the BTresponse signal comprises a preamble or a message.

Clause 79. A non-transitory computer-readable medium storingcomputer-executable instructions that, when executed by an initiatoruser equipment (UE), cause the UE to: transmit a sidelink beam training(BT) reference signal (BTRS) a first number of times on each of a firstset of beams; transmit a sidelink discovery message a second number oftimes on each of a second set of beams, wherein each beam from thesecond set of beams is associated with at least one beam from the firstset of beams; and receive, from at least one responder UE after thetransmission of the sidelink BTRSs and the sidelink discovery messages,a BT response signal and a sidelink discovery response message on a beamcorresponding to one of the first set of beams.

Clause 80. The non-transitory computer-readable medium of clause 79,wherein the transmission of the sidelink discovery messages follows thetransmission of the sidelink BTRSs.

Clause 81. The non-transitory computer-readable medium of any of clauses79 to 80, wherein the transmission of the sidelink BTRSs follows thetransmission of the sidelink discovery messages.

Clause 82. The non-transitory computer-readable medium of any of clauses79 to 81, wherein the first number of times is the same as the secondnumber of times.

Clause 83. The non-transitory computer-readable medium of any of clauses79 to 82, wherein the first number of times is greater than the secondnumber of times.

Clause 84. The non-transitory computer-readable medium of any of clauses79 to 83, wherein each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

Clause 85. The non-transitory computer-readable medium of clause 84,wherein there is a 1:1 mapping between the first set of beams and thesecond set of beams.

Clause 86. The non-transitory computer-readable medium of any of clauses79 to 85, wherein each beam among the first set of beams is associatedwith a first width, and wherein each beam among the second set of beamsis associated with a second width that is wider than the first width.

Clause 87. The non-transitory computer-readable medium of clause 86,wherein there is a N:1 mapping between the first set of beams and thesecond set of beams, with N being greater than 1.

Clause 88. The non-transitory computer-readable medium of any of clauses79 to 87, wherein two or more beams among the first set of beamscorrespond to a single beam among the second set of beams.

Clause 89. The non-transitory computer-readable medium of any of clauses79 to 88, wherein the sidelink BTRSs are transmitted in order betweensuccessively adjacent beams among the first set of beams, or wherein thesidelink discovery messages are transmitted in order betweensuccessively adjacent beams among the second set of beams, or acombination thereof.

Clause 90. The non-transitory computer-readable medium of any of clauses79 to 89, wherein the sidelink BTRSs are transmitted via interleaving ofthe first set of beams, or wherein the sidelink discovery messages aretransmitted via interleaving of the second set of beams, or acombination thereof.

Clause 91. The non-transitory computer-readable medium of any of clauses79 to 90, wherein the BT response signal comprises a preamble or amessage.

Clause 92. A non-transitory computer-readable medium storingcomputer-executable instructions that, when executed by a responder userequipment (UE), cause the UE to: receive, from an initiator UE, asidelink beam training (BT) reference signal (BTRS) a first number oftimes on each of a first set of beams; receive, from the initiator UE, asidelink discovery message a second number of times on each of a secondset of beams, wherein each beam from the second set of beams isassociated with at least one beam from the first set of beams; andtransmit, to the initiator UE, a BT response signal and a sidelinkdiscovery response message on a beam that corresponds to one of thefirst set of beams.

Clause 93. The non-transitory computer-readable medium of clause 92,wherein the reception of the sidelink discovery messages follows thereception of the sidelink BTRSs.

Clause 94. The non-transitory computer-readable medium of any of clauses92 to 93, wherein the reception of the sidelink BTRSs follows thereception of the sidelink discovery messages.

Clause 95. The non-transitory computer-readable medium of any of clauses92 to 94, wherein the first number of times is the same as the secondnumber of times.

Clause 96. The non-transitory computer-readable medium of any of clauses92 to 95, wherein the first number of times is greater than the secondnumber of times.

Clause 97. The non-transitory computer-readable medium of any of clauses92 to 96, wherein each beam among the first set of beams is associatedwith the same width as each beam among the second set of beams.

Clause 98. The non-transitory computer-readable medium of clause 97,wherein there is a 1:1 mapping between the first set of beams and thesecond set of beams.

Clause 99. The non-transitory computer-readable medium of any of clauses92 to 98, wherein each beam among the first set of beams is associatedwith a first width, and wherein each beam among the second set of beamsis associated with a second width that is wider than the first width.

Clause 100. The non-transitory computer-readable medium of clause 99,wherein there is a N:1 mapping between the first set of beams and thesecond set of beams, with N being greater than 1.

Clause 101. The non-transitory computer-readable medium of any ofclauses 92 to 100, wherein two or more beams among the first set ofbeams correspond to a single beam among the second set of beams.

Clause 102. The non-transitory computer-readable medium of any ofclauses 92 to 101, wherein the sidelink BTRSs are received in orderbetween successively adjacent beams among the first set of beams, orwherein the sidelink discovery messages are received in order betweensuccessively adjacent beams among the second set of beams, or acombination thereof.

Clause 103. The non-transitory computer-readable medium of any ofclauses 92 to 102, wherein the sidelink BTRSs are received viainterleaving of the first set of beams, or wherein the sidelinkdiscovery messages are received via interleaving of the second set ofbeams, or a combination thereof.

Clause 104. The non-transitory computer-readable medium of any ofclauses 92 to 103, wherein the BT response signal comprises a preambleor a message.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an ASIC, a field-programmable gate array (FPGA), or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general-purpose processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,for example, a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The methods, sequences and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), flashmemory, read-only memory (ROM), erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), registers, hard disk, aremovable disk, a CD-ROM, or any other form of storage medium known inthe art. An example storage medium is coupled to the processor such thatthe processor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal (e.g., UE). In thealternative, the processor and the storage medium may reside as discretecomponents in a user terminal.

In one or more example aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and Blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects of thedisclosure, it should be noted that various changes and modificationscould be made herein without departing from the scope of the disclosureas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the aspects of the disclosuredescribed herein need not be performed in any particular order.Furthermore, although elements of the disclosure may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A method of operating an initiator user equipment(UE), comprising: transmitting a sidelink beam training (BT) referencesignal (BTRS) a first number of times on each of a first set of beams;transmitting a sidelink discovery message a second number of times oneach of a second set of beams, wherein each beam from the second set ofbeams is associated with at least one beam from the first set of beams;and receiving, from at least one responder UE after the transmission ofthe sidelink BTRSs and the sidelink discovery messages, a BT responsesignal and a sidelink discovery response message on a beam correspondingto one of the first set of beams.
 2. The method of claim 1, wherein thetransmission of the sidelink discovery messages follows the transmissionof the sidelink BTRSs.
 3. The method of claim 1, wherein thetransmission of the sidelink BTRSs follows the transmission of thesidelink discovery messages.
 4. The method of claim 1, wherein the firstnumber of times is the same as the second number of times.
 5. The methodof claim 1, wherein the first number of times is greater than the secondnumber of times.
 6. The method of claim 1, wherein for each beam in thefirst set of beams there is a corresponding beam in the second set ofbeams.
 7. The method of claim 1, wherein two or more beams among thefirst set of beams correspond to a single beam among the second set ofbeams.
 8. The method of claim 1, wherein the sidelink BTRSs aretransmitted in order between successively adjacent beams among the firstset of beams, or wherein the sidelink discovery messages are transmittedin order between successively adjacent beams among the second set ofbeams, or a combination thereof.
 9. The method of claim 1, wherein thesidelink BTRSs are transmitted via unordered beam sweeping of the firstset of beams, or wherein the sidelink discovery messages are transmittedvia unordered beam sweeping of the second set of beams, or a combinationthereof.
 10. The method of claim 1, wherein the BT response signalcomprises a preamble or a message.
 11. The method of claim 1, wherein anoverhead associated with transmission of the BTRS the first number oftimes on each of the first set of beams, transmission the sidelinkdiscovery message the second number of times on each of the second setof beams, and reception of the BT response signal and the sidelinkdiscovery response message is:N×M×BTRS+N×U×BT_Resp+N×DISC+V×DISC_Resp, wherein numbers of the firstset of beams and the second set of beams are each equal to N, wherein Mis a number of receive beams associated with each responder UE, whereinV is a number of UEs among the at least one responder UE, BTRS is anumber of resource blocks (RBs) occupied per BTRS, DISC is a number ofRBs occupied per sidelink discovery message, BT_Resp is a number of RBsoccupied per BT response signal, and DISC_Resp is a number of RBsoccupied per sidelink discovery response message.
 12. The method ofclaim 1, wherein an overhead associated with transmission of the BTRSthe first number of times on each of the first set of beams,transmission the sidelink discovery message the second number of timeson each of the second set of beams, and reception of the BT responsesignal and the sidelink discovery response message is:N×M×(BTRS+DISC)+N×V×BT_Resp+V×DISC_Resp, wherein numbers of the firstset of beams and the second set of beams are each equal to N, wherein Mis a number of receive beams associated with each responder UE, whereinV is a number of UEs among the at least one responder UE, BTRS is anumber of resource blocks (RBs) occupied per BTRS, DISC is a number ofRBs occupied per sidelink discovery message, BT_Resp is a number of RBsoccupied per BT response signal, and DISC_Resp is a number of RBsoccupied per sidelink discovery response message.
 13. The method ofclaim 1, wherein the first set of beams includes two or more beams, andthe second set of beams includes two or more beams.
 14. A method ofoperating responder user equipment (UE), comprising: receiving, from aninitiator UE, a sidelink beam training (BT) reference signal (BTRS) afirst number of times on each of a first set of beams; receiving, fromthe initiator UE, a sidelink discovery message a second number of timeson each of a second set of beams, wherein each beam from the second setof beams is associated with at least one beam from the first set ofbeams; and transmitting, to the initiator UE, a BT response signal and asidelink discovery response message on a beam that corresponds to one ofthe first set of beams.
 15. The method of claim 14, wherein thereception of the sidelink discovery messages follows the reception ofthe sidelink BTRSs.
 16. The method of claim 14, wherein the reception ofthe sidelink BTRSs follows the reception of the sidelink discoverymessages.
 17. The method of claim 16, wherein timing information orresource information or both associated with the sidelink BTRSs is knownbased on the reception of the sidelink discovery messages.
 18. Themethod of claim 14, wherein the first number of times is the same as thesecond number of times.
 19. The method of claim 14, wherein the firstnumber of times is greater than the second number of times.
 20. Themethod of claim 14, wherein for each beam in the first set of beamsthere is a corresponding beam in the second set of beams.
 21. The methodof claim 14, wherein the sidelink BTRSs are received in order betweensuccessively adjacent beams among the first set of beams, or wherein thesidelink discovery messages are received in order between successivelyadjacent beams among the second set of beams, or a combination thereof.22. The method of claim 14, wherein the sidelink BTRSs are received viaunordered beam sweeping of the first set of beams, or wherein thesidelink discovery messages are received via unordered beam sweeping ofthe second set of beams, or a combination thereof.
 23. The method ofclaim 14, wherein the BT response signal comprises a preamble or amessage.
 24. The method of claim 14, wherein an overhead associated withreception of the BTRS the first number of times on each of the first setof beams, reception the sidelink discovery message the second number oftimes on each of the second set of beams, and transmission of the BTresponse signal and the sidelink discovery response message is:N×M×BTRS+N×U×BT_Resp+N×DISC+V×DISC_Resp, wherein numbers of the firstset of beams and the second set of beams are each equal to N, wherein Mis a number of receive beams associated with each responder UE, whereinV is a number of UEs among the at least one responder UE, BTRS is anumber of resource blocks (RBs) occupied per BTRS, DISC is a number ofRBs occupied per sidelink discovery message, BT_Resp is a number of RBsoccupied per BT response signal, and DISC_Resp is a number of RBsoccupied per sidelink discovery response message.
 25. The method ofclaim 14, wherein an overhead associated with reception of the BTRS thefirst number of times on each of the first set of beams, reception thesidelink discovery message the second number of times on each of thesecond set of beams, and transmission of the BT response signal and thesidelink discovery response message is:N×M×(BTRS+DISC)+N×V×BT_Resp+V×DISC_Resp, wherein numbers of the firstset of beams and the second set of beams are each equal to N, wherein Mis a number of receive beams associated with each responder UE, whereinV is a number of UEs among the at least one responder UE, BTRS is anumber of resource blocks (RBs) occupied per BTRS, DISC is a number ofRBs occupied per sidelink discovery message, BT_Resp is a number of RBsoccupied per BT response signal, and DISC_Resp is a number of RBsoccupied per sidelink discovery response message.
 26. An initiator userequipment (UE), comprising: a memory; at least one transceiver; and atleast one processor communicatively coupled to the memory and the atleast one transceiver, the at least one processor configured to:transmit, via the at least one transceiver, a sidelink beam training(BT) reference signal (BTRS) a first number of times on each of a firstset of beams; transmit, via the at least one transceiver, a sidelinkdiscovery message a second number of times on each of a second set ofbeams, wherein each beam from the second set of beams is associated withat least one beam from the first set of beams; and receive, via the atleast one transceiver, from at least one responder UE after thetransmission of the sidelink BTRSs and the sidelink discovery messages,a BT response signal and a sidelink discovery response message on a beamcorresponding to one of the first set of beams.
 27. The initiator UE ofclaim 26, wherein the sidelink BTRSs are transmitted in order betweensuccessively adjacent beams among the first set of beams, or wherein thesidelink discovery messages are transmitted in order betweensuccessively adjacent beams among the second set of beams, or whereinthe sidelink BTRSs are transmitted via interleaving of the first set ofbeams, or wherein the sidelink discovery messages are transmitted viainterleaving of the second set of beams, or a combination thereof.
 28. Aresponder user equipment (UE), comprising: a memory; at least onetransceiver; and at least one processor communicatively coupled to thememory and the at least one transceiver, the at least one processorconfigured to: receive, via the at least one transceiver, from aninitiator UE, a sidelink beam training (BT) reference signal (BTRS) afirst number of times on each of a first set of beams; receive, via theat least one transceiver, from the initiator UE, a sidelink discoverymessage a second number of times on each of a second set of beams,wherein each beam from the second set of beams is associated with atleast one beam from the first set of beams; and transmit, via the atleast one transceiver, to the initiator UE, a BT response signal and asidelink discovery response message on a beam that corresponds to one ofthe first set of beams.
 29. The responder UE of claim 28, wherein thesidelink BTRSs are received in order between successively adjacent beamsamong the first set of beams, or wherein the sidelink discovery messagesare received in order between successively adjacent beams among thesecond set of beams, or wherein the sidelink BTRSs are received viainterleaving of the first set of beams, or wherein the sidelinkdiscovery messages are received via interleaving of the second set ofbeams, or a combination thereof.